l2tp: do not accept arbitrary sockets
[ Upstream commit 17cfe79a65f98abe535261856c5aef14f306dff7 ]
syzkaller found an issue caused by lack of sufficient checks
in l2tp_tunnel_create()
RAW sockets can not be considered as UDP ones for instance.
In another patch, we shall replace all pr_err() by less intrusive
pr_debug() so that syzkaller can find other bugs faster.
Acked-by: Guillaume Nault <g.nault@alphalink.fr>
Acked-by: James Chapman <jchapman@katalix.com>
==================================================================
BUG: KASAN: slab-out-of-bounds in setup_udp_tunnel_sock+0x3ee/0x5f0 net/ipv4/udp_tunnel.c:69
dst_release: dst:00000000d53d0d0f refcnt:-1
Write of size 1 at addr ffff8801d013b798 by task syz-executor3/6242
CPU: 1 PID: 6242 Comm: syz-executor3 Not tainted 4.16.0-rc2+ #253
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report+0x23b/0x360 mm/kasan/report.c:412
__asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435
setup_udp_tunnel_sock+0x3ee/0x5f0 net/ipv4/udp_tunnel.c:69
l2tp_tunnel_create+0x1354/0x17f0 net/l2tp/l2tp_core.c:1596
pppol2tp_connect+0x14b1/0x1dd0 net/l2tp/l2tp_ppp.c:707
SYSC_connect+0x213/0x4a0 net/socket.c:1640
SyS_connect+0x24/0x30 net/socket.c:1621
do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed