aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorPeter Maydell <peter.maydell@linaro.org>2016-02-09 15:57:11 +0000
committerRiku Voipio <riku.voipio@linaro.org>2016-02-23 21:25:09 +0200
commitb6e17875f2e4d1ebfd45bcb0eed04c3157e86a84 (patch)
treef88b68b7f8d1c4bddac4547cd2b2f2b078265343
parentde3f1b98410e0d5b406a0df3a48547b559d18602 (diff)
linux-user: Don't assert if guest tries shmdt(0)
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 <peter.maydell@linaro.org> Reported-by: Pavel Shamis <pasharesearch@gmail.com> Reviewed-by: Laurent Vivier <laurent@vivier.eu> Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
-rw-r--r--linux-user/syscall.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index dac5518a07..8b76169ca5 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;
}