This is a note to let you know that I've just added the patch titled net_sched: reject TCF_EM_SIMPLE case for complex ematch module to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net_sched-reject-tcf_em_simple-case-for-complex-emat.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 0a00aa3c53265f039db55fe096e83af945ce2028 Author: Cong Wang <cong.wang@xxxxxxxxxxxxx> Date: Sat Dec 17 14:17:07 2022 -0800 net_sched: reject TCF_EM_SIMPLE case for complex ematch module [ Upstream commit 9cd3fd2054c3b3055163accbf2f31a4426f10317 ] When TCF_EM_SIMPLE was introduced, it is supposed to be convenient for ematch implementation: https://lore.kernel.org/all/20050105110048.GO26856@xxxxxxxxxxxxxx/ "You don't have to, providing a 32bit data chunk without TCF_EM_SIMPLE set will simply result in allocating & copy. It's an optimization, nothing more." So if an ematch module provides ops->datalen that means it wants a complex data structure (saved in its em->data) instead of a simple u32 value. We should simply reject such a combination, otherwise this u32 could be misinterpreted as a pointer. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-and-tested-by: syzbot+4caeae4c7103813598ae@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: Jun Nie <jun.nie@xxxxxxxxxx> Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx> Cc: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx> Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sched/ematch.c b/net/sched/ematch.c index a48dca26f178..e6078a3da76a 100644 --- a/net/sched/ematch.c +++ b/net/sched/ematch.c @@ -259,6 +259,8 @@ static int tcf_em_validate(struct tcf_proto *tp, * the value carried. */ if (em_hdr->flags & TCF_EM_SIMPLE) { + if (em->ops->datalen > 0) + goto errout; if (data_len < sizeof(u32)) goto errout; em->data = *(u32 *) data;