diff mbox series

[2/2] 9p: clear dangling pointers in p9stat_free

Message ID 1535410108-20650-2-git-send-email-asmadeus@codewreck.org
State Not Applicable, archived
Delegated to: David Miller
Headers show
Series [1/2] v9fs_dir_readdir: fix double-free on p9stat_read error | expand

Commit Message

Dominique Martinet Aug. 27, 2018, 10:48 p.m. UTC 
From: Dominique Martinet <dominique.martinet@cea.fr>

p9stat_free is more of a cleanup function than a 'free' function as it
only frees the content of the struct; there are chances of use-after-free
if it is improperly used (e.g. p9stat_free called twice as it used to be
possible to)

Clearing dangling pointers makes the function idempotent and safer to use.

Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Reported-by: syzbot+d4252148d198410b864f@syzkaller.appspotmail.com
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Latchesar Ionkov <lucho@ionkov.net>
---
 net/9p/protocol.c | 5 +++++
 1 file changed, 5 insertions(+)
diff mbox series

Patch

diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 4a1e1dd30b52..ee32bbf12675 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -46,10 +46,15 @@  p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...);
 void p9stat_free(struct p9_wstat *stbuf)
 {
 	kfree(stbuf->name);
+	stbuf->name = NULL;
 	kfree(stbuf->uid);
+	stbuf->uid = NULL;
 	kfree(stbuf->gid);
+	stbuf->gid = NULL;
 	kfree(stbuf->muid);
+	stbuf->muid = NULL;
 	kfree(stbuf->extension);
+	stbuf->extension = NULL;
 }
 EXPORT_SYMBOL(p9stat_free);