From: Xin Long lucien.xin@gmail.com
stable inclusion from linux-4.19.199 commit 50b57223da67653c61e405d0a7592355cfe4585e
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[ Upstream commit 58acd10092268831e49de279446c314727101292 ]
syzbot reported a call trace:
BUG: KASAN: use-after-free in sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112 Call Trace: sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112 sctp_set_owner_w net/sctp/socket.c:131 [inline] sctp_sendmsg_to_asoc+0x152e/0x2180 net/sctp/socket.c:1865 sctp_sendmsg+0x103b/0x1d30 net/sctp/socket.c:2027 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:821 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:723
This is an use-after-free issue caused by not updating asoc->shkey after it was replaced in the key list asoc->endpoint_shared_keys, and the old key was freed.
This patch is to fix by also updating active_key for asoc when old key is being replaced with a new one. Note that this issue doesn't exist in sctp_auth_del_key_id(), as it's not allowed to delete the active_key from the asoc.
Fixes: 1b1e0bc99474 ("sctp: add refcnt support for sh_key") Reported-by: syzbot+b774577370208727d12b@syzkaller.appspotmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- net/sctp/auth.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/sctp/auth.c b/net/sctp/auth.c index 2bd8c80bd85fb..b2ca66c4a21d2 100644 --- a/net/sctp/auth.c +++ b/net/sctp/auth.c @@ -883,6 +883,8 @@ int sctp_auth_set_key(struct sctp_endpoint *ep, if (replace) { list_del_init(&shkey->key_list); sctp_auth_shkey_release(shkey); + if (asoc && asoc->active_key_id == auth_key->sca_keynumber) + sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL); } list_add(&cur_key->key_list, sh_keys);