From: Jiayuan Chen xfrm6_get_saddr() does not check the return value of ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable source address (returns -EADDRNOTAVAIL), saddr->in6 is left uninitialized, but xfrm6_get_saddr() still returns 0 (success). This causes the caller xfrm_tmpl_resolve_one() to use the uninitialized address in xfrm_state_find(), triggering KMSAN warning: ===================================================== BUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940 xfrm_state_find+0x2424/0xa940 xfrm_resolve_and_create_bundle+0x906/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 xfrm_lookup_route+0x63/0x2b0 ip_route_output_flow+0x1ce/0x270 udp_sendmsg+0x2ce1/0x3400 inet_sendmsg+0x1ef/0x2a0 __sock_sendmsg+0x278/0x3d0 __sys_sendto+0x593/0x720 __x64_sys_sendto+0x130/0x200 x64_sys_call+0x332b/0x3e70 do_syscall_64+0xd3/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f Local variable tmp.i.i created at: xfrm_resolve_and_create_bundle+0x3e3/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 ===================================================== Fix by checking the return value of ipv6_dev_get_saddr() and propagating the error. Fixes: a1e59abf8249 ("[XFRM]: Fix wildcard as tunnel source") Reported-by: syzbot+e136d86d34b42399a8b1@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68bf1024.a70a0220.7a912.02c2.GAE@google.com/T/ Signed-off-by: Jiayuan Chen Signed-off-by: Jiayuan Chen --- net/ipv6/xfrm6_policy.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index 1f19b6f14484..125ea9a5b8a0 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -57,6 +57,7 @@ static int xfrm6_get_saddr(xfrm_address_t *saddr, struct dst_entry *dst; struct net_device *dev; struct inet6_dev *idev; + int err; dst = xfrm6_dst_lookup(params); if (IS_ERR(dst)) @@ -68,9 +69,11 @@ static int xfrm6_get_saddr(xfrm_address_t *saddr, return -EHOSTUNREACH; } dev = idev->dev; - ipv6_dev_get_saddr(dev_net(dev), dev, ¶ms->daddr->in6, 0, - &saddr->in6); + err = ipv6_dev_get_saddr(dev_net(dev), dev, ¶ms->daddr->in6, 0, + &saddr->in6); dst_release(dst); + if (err) + return -EHOSTUNREACH; return 0; } -- 2.43.0