From: Xin Long lucien.xin@gmail.com
commit a1a7e3a36e01ca6e67014f8cf673cb8e47be5550 upstream.
Without doing verify_sec_ctx_len() check in xfrm_add_acquire(), it may be out-of-bounds to access uctx->ctx_str with uctx->ctx_len, as noticed by syz:
BUG: KASAN: slab-out-of-bounds in selinux_xfrm_alloc_user+0x237/0x430 Read of size 768 at addr ffff8880123be9b4 by task syz-executor.1/11650
Call Trace: dump_stack+0xe8/0x16e print_address_description.cold.3+0x9/0x23b kasan_report.cold.4+0x64/0x95 memcpy+0x1f/0x50 selinux_xfrm_alloc_user+0x237/0x430 security_xfrm_policy_alloc+0x5c/0xb0 xfrm_policy_construct+0x2b1/0x650 xfrm_add_acquire+0x21d/0xa10 xfrm_user_rcv_msg+0x431/0x6f0 netlink_rcv_skb+0x15a/0x410 xfrm_netlink_rcv+0x6d/0x90 netlink_unicast+0x50e/0x6a0 netlink_sendmsg+0x8ae/0xd40 sock_sendmsg+0x133/0x170 ___sys_sendmsg+0x834/0x9a0 __sys_sendmsg+0x100/0x1e0 do_syscall_64+0xe5/0x660 entry_SYSCALL_64_after_hwframe+0x6a/0xdf
So fix it by adding the missing verify_sec_ctx_len check there.
Fixes: 980ebd25794f ("[IPSEC]: Sync series - acquire insert") Reported-by: Hangbin Liu liuhangbin@gmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/xfrm/xfrm_user.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -2276,6 +2276,9 @@ static int xfrm_add_acquire(struct sk_bu err = verify_newpolicy_info(&ua->policy); if (err) goto free_state; + err = verify_sec_ctx_len(attrs); + if (err) + goto free_state;
/* build an XP */ xp = xfrm_policy_construct(net, &ua->policy, attrs, &err);