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authorRobert Doebbelin <robert@quobyte.com>2016-03-07 09:50:56 +0100
committerMiklos Szeredi <miklos@szeredi.hu>2016-03-14 15:02:50 +0100
commit7cabc61e01a0a8b663bd2b4c982aa53048218734 (patch)
tree474f0a6e0cde183d19ccb0c9b14d2358e1944012 /fs/fuse
parentb562e44f507e863c6792946e4e1b1449fbbac85d (diff)
downloadlinux-7cabc61e01a0a8b663bd2b4c982aa53048218734.tar.bz2
fuse: do not use iocb after it may have been freed
There's a race in fuse_direct_IO(), whereby is_sync_kiocb() is called on an iocb that could have been freed if async io has already completed. The fix in this case is simple and obvious: cache the result before starting io. It was discovered by KASan: kernel: ================================================================== kernel: BUG: KASan: use after free in fuse_direct_IO+0xb1a/0xcc0 at addr ffff88036c414390 Signed-off-by: Robert Doebbelin <robert@quobyte.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: bcba24ccdc82 ("fuse: enable asynchronous processing direct IO") Cc: <stable@vger.kernel.org> # 3.10+
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/file.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index b03d253ece15..34a23df361ca 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2843,6 +2843,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
loff_t i_size;
size_t count = iov_iter_count(iter);
struct fuse_io_priv *io;
+ bool is_sync = is_sync_kiocb(iocb);
pos = offset;
inode = file->f_mapping->host;
@@ -2882,11 +2883,11 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
* to wait on real async I/O requests, so we must submit this request
* synchronously.
*/
- if (!is_sync_kiocb(iocb) && (offset + count > i_size) &&
+ if (!is_sync && (offset + count > i_size) &&
iov_iter_rw(iter) == WRITE)
io->async = false;
- if (io->async && is_sync_kiocb(iocb))
+ if (io->async && is_sync)
io->done = &wait;
if (iov_iter_rw(iter) == WRITE) {
@@ -2900,7 +2901,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
/* we have a non-extending, async request, so return */
- if (!is_sync_kiocb(iocb))
+ if (!is_sync)
return -EIOCBQUEUED;
wait_for_completion(&wait);