[PATCH 3.19.y-ckt 147/196] do_last(): don't let a bogus return value from ->open() et.al. to confuse us

From: Kamal Mostafa
Date: Tue Mar 08 2016 - 19:50:43 EST

3.19.8-ckt16 -stable review patch. If anyone has any objections, please let me know.


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit c80567c82ae4814a41287618e315a60ecf513be6 upstream.

... into returning a positive to path_openat(), which would interpret that
as "symlink had been encountered" and proceed to corrupt memory, etc.
It can only happen due to a bug in some ->open() instance or in some LSM
hook, etc., so we report any such event *and* make sure it doesn't trick
us into further unpleasantness.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
fs/namei.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index f38cb09..6c363c9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3124,6 +3124,10 @@ opened:
goto exit_fput;
+ if (unlikely(error > 0)) {
+ WARN_ON(1);
+ error = -EINVAL;
+ }
if (got_write)