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 09:45:26 +0100 |
| commit | 242e20a5b3cc2b99ace977546d3cffc6a2a35991 (patch) | |
| tree | 7ab252d2924509fa25a30331365905722805452b | |
| parent | 0382becc1d24e1cd00dc44e1fa5f7655441c258c (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 0f695df14c9d..372ce9913e6d 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -765,10 +765,12 @@ 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; |