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Commit 36c99a16 authored by Dominique Martinet's avatar Dominique Martinet Committed by Greg Kroah-Hartman
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9p: clear dangling pointers in p9stat_free 

[ 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@codewreck.org


Signed-off-by: default avatarDominique Martinet <dominique.martinet@cea.fr>
Reported-by: default avatar <syzbot+d4252148d198410b864f@syzkaller.appspotmail.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7e0a5da5

net/9p/protocol.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -46,10 +46,15 @@ p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...); 
void p9stat_free(struct p9_wstat *stbuf)

void p9stat_free(struct p9_wstat *stbuf)

{

{

	kfree(stbuf->name);

	kfree(stbuf->name);

	stbuf->name = NULL;

	kfree(stbuf->uid);

	kfree(stbuf->uid);

	stbuf->uid = NULL;

	kfree(stbuf->gid);

	kfree(stbuf->gid);

	stbuf->gid = NULL;

	kfree(stbuf->muid);

	kfree(stbuf->muid);

	stbuf->muid = NULL;

	kfree(stbuf->extension);

	kfree(stbuf->extension);

	stbuf->extension = NULL;

}

}

EXPORT_SYMBOL(p9stat_free);

EXPORT_SYMBOL(p9stat_free);