diff options
| author | Ben Hutchings <ben@decadent.org.uk> | 2018-02-04 05:06:27 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-25 13:05:44 +0300 |
| commit | 2dfe49da487cf92b45083deb38e37062a5b8f83e (patch) | |
| tree | afc6e32819af6113a066ed0a9e08e0186a60a7d1 | |
| parent | fedae0f64845933a0f28604a09be2e0323d66236 (diff) | |
| download | linux-2dfe49da487cf92b45083deb38e37062a5b8f83e.tar.xz | |
staging: android: ashmem: Fix a race condition in pin ioctls
commit ce8a3a9e76d0193e2e8d74a06d275b3c324ca652 upstream.
ashmem_pin_unpin() reads asma->file and asma->size before taking the
ashmem_mutex, so it can race with other operations that modify them.
Build-tested only.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/android/ashmem.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index 558a66b459fa..d08324998933 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -719,30 +719,32 @@ static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, size_t pgstart, pgend; int ret = -EINVAL; + mutex_lock(&ashmem_mutex); + if (unlikely(!asma->file)) - return -EINVAL; + goto out_unlock; - if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) - return -EFAULT; + if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) { + ret = -EFAULT; + goto out_unlock; + } /* per custom, you can pass zero for len to mean "everything onward" */ if (!pin.len) pin.len = PAGE_ALIGN(asma->size) - pin.offset; if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) - return -EINVAL; + goto out_unlock; if (unlikely(((__u32)-1) - pin.offset < pin.len)) - return -EINVAL; + goto out_unlock; if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) - return -EINVAL; + goto out_unlock; pgstart = pin.offset / PAGE_SIZE; pgend = pgstart + (pin.len / PAGE_SIZE) - 1; - mutex_lock(&ashmem_mutex); - switch (cmd) { case ASHMEM_PIN: ret = ashmem_pin(asma, pgstart, pgend); @@ -755,6 +757,7 @@ static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, break; } +out_unlock: mutex_unlock(&ashmem_mutex); return ret; |