Re: [Qemu-devel] valgrind problem in sun4u_load_kernel()

[Mark Cave-Ayland]

On 15/06/18 11:37, Thomas Huth wrote:

>   Hi Mark, hi Artyom,
>
> while using valgrind to fix some issues with the rom_ptr() function
> today, I noticed that there is one more problem in sun4u_load_kernel():
> The kernel_top variable can be used uninitialized in some cases:
> If load_elf() fails and the kernel is loaded via load_aout() or
> load_image_targphys(), the kernel_top variable is never set to a valid
> value. This could cause some trouble when loading the initrd later. When
> you've got some spare time, could you please have a look?

Hmmm that's an interesting one - I'm not immediately aware of any 64-bit 
kernels that are a.out rather than ELF, so I wonder if this has been 
used to run a.out executables on startup? Any thoughts, Artyom?

If this is the case then we can only have a valid kernel_top with an ELF 
kernel then maybe the following is a good enough solution:


diff --git a/hw/sparc64/sun4u.c b/hw/sparc64/sun4u.c
index 3975a7b65a..35acf8c96e 100644
--- a/hw/sparc64/sun4u.c
+++ b/hw/sparc64/sun4u.c
@@ -139,7 +139,7 @@ static uint64_t sun4u_load_kernel(const char 
*kernel_filename,
     unsigned int i;
     long kernel_size;
     uint8_t *ptr;
-    uint64_t kernel_top;
+    uint64_t kernel_top = 0;

     linux_boot = (kernel_filename != NULL);

@@ -172,7 +172,7 @@ static uint64_t sun4u_load_kernel(const char 
*kernel_filename,
         }
         /* load initrd above kernel */
         *initrd_size = 0;
-        if (initrd_filename) {
+        if (initrd_filename && kernel_top) {
             *initrd_addr = TARGET_PAGE_ALIGN(kernel_top);

             *initrd_size = load_image_targphys(initrd_filename,


ATB,

Mark.