diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2016-02-09 15:57:11 +0000 |
|---|---|---|
| committer | Riku Voipio <riku.voipio@linaro.org> | 2016-02-23 21:25:09 +0200 |
| commit | b6e17875f2e4d1ebfd45bcb0eed04c3157e86a84 (patch) | |
| tree | f88b68b7f8d1c4bddac4547cd2b2f2b078265343 | |
| parent | de3f1b98410e0d5b406a0df3a48547b559d18602 (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.c | 12 |
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; } |