4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nikolay Borisov <kernel@xxxxxxxx>
commit 0d7718f666be181fda1ba2d08f137d87c1419347 upstream.
In case __ceph_do_getattr returns an error and the retry_op in
ceph_read_iter is not READ_INLINE, then it's possible to invoke
__free_page on a page which is NULL, this naturally leads to a crash.
This can happen when, for example, a process waiting on a MDS reply
receives sigterm.
Fix this by explicitly checking whether the page is set or not.
Signed-off-by: Nikolay Borisov <kernel@xxxxxxxx>
Reviewed-by: Yan, Zheng <zyan@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ceph/file.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1272,7 +1272,8 @@ again:
statret = __ceph_do_getattr(inode, page,
CEPH_STAT_CAP_INLINE_DATA, !!page);
if (statret < 0) {
- __free_page(page);
+ if (page)
+ __free_page(page);
if (statret == -ENODATA) {
BUG_ON(retry_op != READ_INLINE);
goto again;
--
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