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author | Eric Dumazet <edumazet@google.com> | 2018-03-06 18:54:53 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-08 12:49:42 +0300 |
commit | 2e017ead9b03445338877e951334cda71ac84b65 (patch) | |
tree | 9977e2b6b478834e05f30d63185c77f5d4e05ca6 /net/l2tp | |
parent | c2b32840e2f62938662ae102a4fe5043b92cdcb6 (diff) | |
download | linux-2e017ead9b03445338877e951334cda71ac84b65.tar.xz |
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>
Diffstat (limited to 'net/l2tp')
-rw-r--r-- | net/l2tp/l2tp_core.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index b5f3c175331c..b7f19946a78b 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1517,9 +1517,14 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 encap = cfg->encap; /* Quick sanity checks */ + err = -EPROTONOSUPPORT; + if (sk->sk_type != SOCK_DGRAM) { + pr_debug("tunl %hu: fd %d wrong socket type\n", + tunnel_id, fd); + goto err; + } switch (encap) { case L2TP_ENCAPTYPE_UDP: - err = -EPROTONOSUPPORT; if (sk->sk_protocol != IPPROTO_UDP) { pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP); @@ -1527,7 +1532,6 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 } break; case L2TP_ENCAPTYPE_IP: - err = -EPROTONOSUPPORT; if (sk->sk_protocol != IPPROTO_L2TP) { pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP); |