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authorViktor Slavkovic <viktors@google.com>2018-01-08 10:43:03 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-17 09:38:56 +0100
commitc51d23dffc2e9ca05d611c86c440f9055541c62d (patch)
tree405a27d25ac6548b386dd056837194e59f49ec83 /drivers
parent8ab8c6e6607a14ebd54319535b17e384d2872df9 (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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/staging/android/ashmem.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 2b770cb0c488..558a66b459fa 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -774,10 +774,12 @@ 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;