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[Bug 1920934] Re: Heap-use-after-free in io_writex / cputlb.c results in


From: Richard Henderson
Subject: [Bug 1920934] Re: Heap-use-after-free in io_writex / cputlb.c results in Linux kernel crashes
Date: Wed, 24 Mar 2021 12:26:06 -0000

This suggests that the rcu_read in iotlb_to_section is not
playing well with one of the g_renew calls in softmmu/physmem.c.

Not sure which, since the sanitizer dump above doesn't trace
back beyond glib itself.

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https://bugs.launchpad.net/bugs/1920934

Title:
  Heap-use-after-free in io_writex / cputlb.c results in Linux kernel
  crashes

Status in QEMU:
  New

Bug description:
  qemu version: git 5ca634afcf83215a9a54ca6e66032325b5ffb5f6; 5.2.0

  We've encountered that booting the Linux kernel in TCG mode, results
  in a racy heap-use-after-free. The bug can be detected by ASan [A],
  but in the majority of runs results in a crashing kernel [B].

  To reproduce, the following command line was used:

  $> while ./qemu-system-x86_64 -no-reboot -smp 10 -m 2G -kernel
  arch/x86/boot/bzImage -nographic -append "oops=panic panic_on_warn=1
  panic=1 kfence.sample_interval=1 nokaslr"; do sleep 0.5s; done

  The crashes in the kernel [B] appear to receive an interrupt in a code
  location where the instructions are periodically patched (via the
  jump_label infrastructure).

  [A]:
  =================================================================             
                                                                                
                                                                                
                 
  ==3552508==ERROR: AddressSanitizer: heap-use-after-free on address 
0x6190007fef50 at pc 0x55885b0b4d1b bp 0x7f83baffb800 sp 0x7f83baffb7f8         
                                                                                
                            
  READ of size 8 at 0x6190007fef50 thread T4                                    
                                                                                
                                                                                
                 
  [    4.616506][    T1] pci 0000:00:02.0: reg 0x18: [mem 
0xfebf0000-0xfebf0fff]                                                          
                                                                                
                                       
  [    4.670567][    T1] pci 0000:00:02.0: reg 0x30: [mem 0xfebe0000-0xfebeffff 
pref]                                                                           
                                                                                
                 
  [    4.691345][    T1] pci 0000:00:03.0: [8086:100e] type 00 class 0x020000   
                                                                                
                                                                                
                 
  [    4.701540][    T1] pci 0000:00:03.0: reg 0x10: [mem 
0xfebc0000-0xfebdffff]                                                          
                                                                                
                                       
  [    4.711076][    T1] pci 0000:00:03.0: reg 0x14: [io  0xc000-0xc03f]        
                                                                                
                                                                                
                 
  [    4.746869][    T1] pci 0000:00:03.0: reg 0x30: [mem 0xfeb80000-0xfebbffff 
pref]                                                                           
                                                                                
                 
  [    4.813612][    T1] ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)        
                                                                                
                                                                                
                 
      #0 0x55885b0b4d1a in io_writex ../accel/tcg/cputlb.c:1408                 
                                                                                
                                                                                
                 
      #1 0x55885b0d3b9f in store_helper ../accel/tcg/cputlb.c:2444              
                                                                                
                                                                                
                 
      #2 0x55885b0d3b9f in helper_le_stl_mmu ../accel/tcg/cputlb.c:2510         
                                                                                
                                                                                
                 
  [    4.820927][    T1] ACPI: PCI Interrupt Link [LNKB] (IRQs 5 *10 11)        
                                                                                
                                                                                
                 
      #3 0x7f843cedf8dc  (<unknown module>)                                     
                                                                                
                                                                                
                 
                                                                                
                                                                                
                                                                                
                 
  0x6190007fef50 is located 208 bytes inside of 1024-byte region 
[0x6190007fee80,0x6190007ff280)                                                 
                                                                                
                                
  freed by thread T11 here:                                                     
                                                                                
                                                                                
                 
      #0 0x7f8483f431f8 in __interceptor_realloc 
../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:164                     
                                                                                
                                                
      #1 0x7f8483586de7 in g_realloc 
(/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x57de7)                                
                                                                                
                                                            
                                                                                
                                                                                
                                                                                
                 
  previously allocated by thread T11 here:                                      
                                                                                
                                                                                
                 
      #0 0x7f8483f431f8 in __interceptor_realloc 
../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:164                     
                                                                                
                                                
      #1 0x7f8483586de7 in g_realloc 
(/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x57de7)                                
                                                                                
                                                            
                                                                                
                                                                                
                                                                                
                 
  Thread T4 created by T0 here:                                                 
                                                                                
                                                                                
                 
  [    4.827679][    T1] ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)        
                                                                                
                                                                                
                 
  [    4.835143][    T1] ACPI: PCI Interrupt Link [LNKD] (IRQs 5 10 *11)        
                                                                                
                                                                                
                 
  [    4.838441][    T1] ACPI: PCI Interrupt Link [LNKS] (IRQs *9)              
                                                                                
                                                                                
                 
      #0 0x7f8483eee2a2 in __interceptor_pthread_create 
../../../../src/libsanitizer/asan/asan_interceptors.cpp:214                     
                                                                                
                                         
      #1 0x55885b7cf0de in qemu_thread_create ../util/qemu-thread-posix.c:558   
                                                                                
                                                                                
                 
                                                                                
                                                                                
                                                                                
                 
  Thread T11 created by T0 here:                                                
                                                                                
                                                                                
                 
      #0 0x7f8483eee2a2 in __interceptor_pthread_create 
../../../../src/libsanitizer/asan/asan_interceptors.cpp:214                     
                                                                                
                                         
      #1 0x55885b7cf0de in qemu_thread_create ../util/qemu-thread-posix.c:558   
                                                                                
                                                                                
                 
                                                                                
                   
  SUMMARY: AddressSanitizer: heap-use-after-free ../accel/tcg/cputlb.c:1408 in 
io_writex                                                                       
                                                                                
                  
  Shadow bytes around the buggy address:                                        
                                                                                
                                                                                
                 
    0x0c32800f7d90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00             
                                                                                
                                                                                
                 
    0x0c32800f7da0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00             
                                                                                
                                                                                
                 
    0x0c32800f7db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa             
                                                                                
                                                                                
                 
    0x0c32800f7dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa             
                                                                                
                                                                                
                 
    0x0c32800f7dd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
  =>0x0c32800f7de0: fd fd fd fd fd fd fd fd fd fd[fd]fd fd fd fd fd             
                                                                                
                                                                                
                 
    0x0c32800f7df0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
    0x0c32800f7e00: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
    0x0c32800f7e10: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
    0x0c32800f7e20: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
    0x0c32800f7e30: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd             
                                                                                
                                                                                
                 
  Shadow byte legend (one shadow byte represents 8 application bytes):          
                                                                                
                                                                                
                 
    Addressable:           00                                                   
                                                                                
                                                                                
                 
    Partially addressable: 01 02 03 04 05 06 07                                 
                                                                                
                                                                                
                 
    Heap left redzone:       fa                                                 
                                                                                
                                                                                
                 
    Freed heap region:       fd                                                 
                                                                                
                                                                                
                 
    Stack left redzone:      f1                                                 
                                                                                
                                                                                
                 
    Stack mid redzone:       f2                                                 
                                                                                
                                                                                
                 
    Stack right redzone:     f3                                                 
                                                                                
                                                                                
                 
    Stack after return:      f5                                                 
                                                                                
                                                                                
                 
    Stack use after scope:   f8                                                 
                                                                                
                                                                                
                 
    Global redzone:          f9                                                 
                                                                                
                                                                                
                 
    Global init order:       f6                                                 
                                                                                
                                                                                
                 
    Poisoned by user:        f7                                                 
                                                                                
                                                                                
                 
    Container overflow:      fc                                                 
                                                                                
                                                                                
                 
    Array cookie:            ac                                                 
                                                                                
                                                                                
                 
    Intra object redzone:    bb                                                 
                                                                                
                                                                                
                 
    ASan internal:           fe                                                 
                                                                                
                                                                                
                 
    Left alloca redzone:     ca                                                 
                                                                                
                                                                                
                 
    Right alloca redzone:    cb                                                 
                                                                                
                                                                                
                 
    Shadow gap:              cc                                                 
                                                                                
                                                                                
                 
  ==3552508==ABORTING 

  
  [B]:
  [    6.029269][    C4] int3: 0000 [#1] PREEMPT SMP                            
                                                                                
                                                                                
                 
  [    6.029269][    C4] CPU: 4 PID: 34 Comm: cpuhp/4 Not tainted 5.12.0-rc4 #2 
                                                                                
                                                                                
                 
  [    6.029269][    C4] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), 
BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014                    
                                                                                
                 
  [    6.029269][    C4] RIP: 0010:kmem_cache_alloc_trace+0xdd/0x2f0            
                                                                                
                                                                                
                 
  [    6.029269][    C4] Code: de e8 a7 2e 02 00 85 c0 74 0d 48 89 ef e8 bb 60 
00 00 e9 e3 00 00 00 4d 85 f6 0f 84 da 00 00 00 4c 89 6c 24 08 48 8b 2c 24 cc 
<98> 01 00 00 45 31 ed 4c 89 6c 24 10 4d 85 ed 0f 85 99 00 00 00 49             
                    
  [    6.029269][    C4] RSP: 0018:ffffc90000483cc0 EFLAGS: 00000286            
                                                                                
                                                                                
                 
  [    6.029269][    C4] RAX: 0000000000000000 RBX: 0000000000000dc0 RCX: 
ffff888003b717c0                                                                
                                                                                
                       
  [    6.029269][    C4] RDX: 0000000000000000 RSI: 0000000000000dc0 RDI: 
ffff888003842a00                                                                
                                                                                
                       
  [    6.029269][    C4] RBP: 0000000000000110 R08: 0000000000000000 R09: 
0000000000000000                                                                
                                                                                
                       
  [    6.029269][    C4] R10: ffffffff81248e22 R11: 00000000fa83b201 R12: 
0000000000000dc0                                                                
                                                                                
                       
  [    6.029269][    C4] R13: 0000000000000000 R14: ffff888003842a00 R15: 
ffffffff8150e1c9                                                                
                                                                                
                       
  [    6.029269][    C4] FS:  0000000000000000(0000) GS:ffff88803ea00000(0000) 
knlGS:0000000000000000                                                          
                                                                                
                  
  [    6.029269][    C4] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033      
                                                                                
                                                                                
                 
  [    6.029269][    C4] CR2: 0000000000000000 CR3: 0000000002011000 CR4: 
00000000000006e0                                                                
                                                                                
                       
  [    6.029269][    C4] Call Trace:                                            
                                                                                
                                                                                
                 
  [    6.029269][    C4]  device_add+0x59/0x7b0                                 
                                                                                
                                                                                
                 
  [    6.029269][    C4]  device_create+0xea/0x130                              
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? cpu_report_death+0x40/0x40                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? cpu_report_death+0x40/0x40                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? msr_devnode+0x20/0x20                               
                                                                                
                                                                                
                 
  [    6.029269][    C4]  msr_device_create+0x28/0x40                           
                                                                                
                                                                                
                 
  [    6.029269][    C4]  cpuhp_invoke_callback+0x140/0x2f0                     
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? finish_task_switch+0x8c/0x230                       
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? cpu_report_death+0x40/0x40                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  cpuhp_thread_fun+0x118/0x1a0                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? cpu_report_death+0x40/0x40                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  smpboot_thread_fn+0x1b9/0x270                         
                                                                                
                                                                                
                 
  [    6.029269][    C4]  kthread+0x14b/0x160                                   
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ? kthread_unuse_mm+0xf0/0xf0                          
                                                                                
                                                                                
                 
  [    6.029269][    C4]  ret_from_fork+0x1f/0x30                               
                                                                                
                                                                                
                 
  [    6.029269][    C4] ---[ end trace 1336f71544bb94e4 ]---

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