4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dominique Martinet dominique.martinet@cea.fr
[ 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@codewrec... Signed-off-by: Dominique Martinet dominique.martinet@cea.fr Reported-by: syzbot+d4252148d198410b864f@syzkaller.appspotmail.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/9p/protocol.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/net/9p/protocol.c +++ b/net/9p/protocol.c @@ -46,10 +46,15 @@ p9pdu_writef(struct p9_fcall *pdu, int p 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);