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[Qemu-devel] [PULL v2 4/8] linux-user: Don't assert if guest tries shmdt
From: |
riku . voipio |
Subject: |
[Qemu-devel] [PULL v2 4/8] linux-user: Don't assert if guest tries shmdt(0) |
Date: |
Thu, 25 Feb 2016 13:01:09 +0200 |
From: Peter Maydell <address@hidden>
Our implementation of shmat() and shmdt() for linux-user was
using "zero guest address" as its marker for "entry in the
shm_regions[] array is not in use". This meant that if the
guest did a shmdt(0) we would match on an unused array entry
and call page_set_flags() with both start and end addresses zero,
which causes an assertion failure.
Use an explicit in_use flag to manage the shm_regions[] array,
so that we avoid this problem.
Signed-off-by: Peter Maydell <address@hidden>
Reported-by: Pavel Shamis <address@hidden>
Reviewed-by: Laurent Vivier <address@hidden>
Signed-off-by: Riku Voipio <address@hidden>
---
linux-user/syscall.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index dac5518..8b76169 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2598,8 +2598,9 @@ static abi_long do_socketcall(int num, abi_ulong vptr)
#define N_SHM_REGIONS 32
static struct shm_region {
- abi_ulong start;
- abi_ulong size;
+ abi_ulong start;
+ abi_ulong size;
+ bool in_use;
} shm_regions[N_SHM_REGIONS];
struct target_semid_ds
@@ -3291,7 +3292,8 @@ static inline abi_ulong do_shmat(int shmid, abi_ulong
shmaddr, int shmflg)
((shmflg & SHM_RDONLY)? 0 : PAGE_WRITE));
for (i = 0; i < N_SHM_REGIONS; i++) {
- if (shm_regions[i].start == 0) {
+ if (!shm_regions[i].in_use) {
+ shm_regions[i].in_use = true;
shm_regions[i].start = raddr;
shm_regions[i].size = shm_info.shm_segsz;
break;
@@ -3308,8 +3310,8 @@ static inline abi_long do_shmdt(abi_ulong shmaddr)
int i;
for (i = 0; i < N_SHM_REGIONS; ++i) {
- if (shm_regions[i].start == shmaddr) {
- shm_regions[i].start = 0;
+ if (shm_regions[i].in_use && shm_regions[i].start == shmaddr) {
+ shm_regions[i].in_use = false;
page_set_flags(shmaddr, shmaddr + shm_regions[i].size, 0);
break;
}
--
2.1.4
- [Qemu-devel] [PULL v2 0/8] linux-user updates and fixes, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 1/8] linux-user: fix realloc size of target_fd_trans., riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 3/8] linux-user: set ppc64/ppc64le default CPU to POWER8, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 6/8] linux-user: remove unavailable syscalls from aarch64, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 5/8] linux-user: sync syscall numbers with kernel, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 4/8] linux-user: Don't assert if guest tries shmdt(0),
riku . voipio <=
- [Qemu-devel] [PULL v2 2/8] build: [linux-user] Rename "syscall.h" to "target_syscall.h" in target directories, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 8/8] linux-user: add getrandom() syscall, riku . voipio, 2016/02/25
- [Qemu-devel] [PULL v2 7/8] linux-user: correct timerfd_create syscall numbers, riku . voipio, 2016/02/25
- Re: [Qemu-devel] [PULL v2 0/8] linux-user updates and fixes, Peter Maydell, 2016/02/25