From: Dominique Martinet <dominique.martinet@xxxxxx> [ Upstream commit 62e3941776fea8678bb8120607039410b1b61a65 ] 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. Link: http://lkml.kernel.org/r/1535410108-20650-2-git-send-email-asmadeus@xxxxxxxxxxxxx Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxx> Reported-by: syzbot+d4252148d198410b864f@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/9p/protocol.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/9p/protocol.c b/net/9p/protocol.c index 16e10680518c..9743837aebc6 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); -- 2.17.1
