[15/68] CRED: Fix kernel panic upon security_file_alloc() failure.

From: Greg KH
Date: Mon Feb 28 2011 - 11:50:24 EST

2.6.32-longterm review patch. If anyone has any objections, please let us know.


From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

commit 78d2978874e4e10e97dfd4fd79db45bdc0748550 upstream.

In get_empty_filp() since 2.6.29, file_free(f) is called with f->f_cred == NULL
when security_file_alloc() returned an error. As a result, kernel will panic()
due to put_cred(NULL) call within RCU callback.

Fix this bug by assigning f->f_cred before calling security_file_alloc().

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

fs/file_table.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -121,13 +121,13 @@ struct file *get_empty_filp(void)
goto fail;

+ f->f_cred = get_cred(cred);
if (security_file_alloc(f))
goto fail_sec;

atomic_long_set(&f->f_count, 1);
- f->f_cred = get_cred(cred);
/* f->f_version: 0 */

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