diff options
| author | Viktor Slavkovic <viktors@google.com> | 2018-01-08 10:43:03 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-17 09:35:32 +0100 |
| commit | b4106c55b574fe37900b02ddf89cbe4b9d971392 (patch) | |
| tree | ae4ffb1b9d2a09961df6c2f424510a556566f595 | |
| parent | 27a194bc8d218ed7e1aa9e10b67f5af6388c69b3 (diff) | |
staging: android: ashmem: fix a race condition in ASHMEM_SET_SIZE ioctl
commit 443064cb0b1fb4569fe0a71209da7625129fb760 upstream.
A lock-unlock is missing in ASHMEM_SET_SIZE ioctl which can result in a
race condition when mmap is called. After the !asma->file check, before
setting asma->size, asma->file can be set in mmap. That would result in
having different asma->size than the mapped memory size. Combined with
ASHMEM_UNPIN ioctl and shrinker invocation, this can result in memory
corruption.
Signed-off-by: Viktor Slavkovic <viktors@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/android/ashmem.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index 9c6357c03905..b64327722660 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -759,10 +759,12 @@ static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) break; case ASHMEM_SET_SIZE: ret = -EINVAL; + mutex_lock(&ashmem_mutex); if (!asma->file) { ret = 0; asma->size = (size_t)arg; } + mutex_unlock(&ashmem_mutex); break; case ASHMEM_GET_SIZE: ret = asma->size; |