Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Fri, 24 Apr 2020 00:07:14 +0100 | Subject | [PATCH 3.16 207/245] net_sched: fix datalen for ematch |
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3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Cong Wang <xiyou.wangcong@gmail.com>
commit 61678d28d4a45ef376f5d02a839cc37509ae9281 upstream.
syzbot reported an out-of-bound access in em_nbyte. As initially analyzed by Eric, this is because em_nbyte sets its own em->datalen in em_nbyte_change() other than the one specified by user, but this value gets overwritten later by its caller tcf_em_validate(). We should leave em->datalen untouched to respect their choices.
I audit all the in-tree ematch users, all of those implement ->change() set em->datalen, so we can just avoid setting it twice in this case.
Reported-and-tested-by: syzbot+5af9a90dad568aa9f611@syzkaller.appspotmail.com Reported-by: syzbot+2f07903a5b05e7f36410@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/sched/ematch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/sched/ematch.c +++ b/net/sched/ematch.c @@ -266,12 +266,12 @@ static int tcf_em_validate(struct tcf_pr } em->data = (unsigned long) v; } + em->datalen = data_len; } } em->matchid = em_hdr->matchid; em->flags = em_hdr->flags; - em->datalen = data_len; err = 0; errout:
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