[PATCH 4.9 009/171] xfrm: validate template mode

Greg Kroah-Hartman
2018-11-08T21:49:39Z

[ Upstream commit 32bf94fb5c2ec4ec842152d0e5937cd4bb6738fa ]

XFRM mode parameters passed as part of the user templates
in the IP_XFRM_POLICY are never properly validated. Passing
values other than valid XFRM modes can cause stack-out-of-bounds
reads to occur later in the XFRM processing:

[ 140.535608] ================================================================
[ 140.543058] BUG: KASAN: stack-out-of-bounds in xfrm_state_find+0x17e4/0x1cc4
[ 140.550306] Read of size 4 at addr ffffffc0238a7a58 by task repro/5148
[ 140.557369]
[ 140.558927] Call trace:
[ 140.558936] dump_backtrace+0x0/0x388
[ 140.558940] show_stack+0x24/0x30
[ 140.558946] __dump_stack+0x24/0x2c
[ 140.558949] dump_stack+0x8c/0xd0
[ 140.558956] print_address_description+0x74/0x234
[ 140.558960] kasan_report+0x240/0x264
[ 140.558963] __asan_report_load4_noabort+0x2c/0x38
[ 140.558967] xfrm_state_find+0x17e4/0x1cc4
[ 140.558971] xfrm_resolve_and_create_bundle+0x40c/0x1fb8
[ 140.558975] xfrm_lookup+0x238/0x1444
[ 140.558977] xfrm_lookup_route+0x48/0x11c
[ 140.558984] ip_route_output_flow+0x88/0xc4
[ 140.558991] raw_sendmsg+0xa74/0x266c
[ 140.558996] inet_sendmsg+0x258/0x3b0
[ 140.559002] sock_sendmsg+0xbc/0xec
[ 140.559005] SyS_sendto+0x3a8/0x5a8
[ 140.559008] el0_svc_naked+0x34/0x38
[ 140.559009]
[ 140.592245] page dumped because: kasan: bad access detected
[ 140.597981] page_owner info is not active (free page?)
[ 140.603267]
[ 140.653503] ================================================================

Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/xfrm/xfrm_user.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index b7ac834a6091..026770884d46 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1412,6 +1412,9 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family)
(ut[i].family != prev_family))
return -EINVAL;

+ if (ut[i].mode >= XFRM_MODE_MAX)
+ return -EINVAL;
+
prev_family = ut[i].family;

switch (ut[i].family) {
--
2.17.1