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Subject[PATCH 4.16 51/81] net: validate attribute sizes in neigh_dump_table()
Date
4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit 7dd07c143a4b54d050e748bee4b4b9e94a7b1744 ]

Since neigh_dump_table() calls nlmsg_parse() without giving policy
constraints, attributes can have arbirary size that we must validate

Reported by syzbot/KMSAN :

BUG: KMSAN: uninit-value in neigh_master_filtered net/core/neighbour.c:2292 [inline]
BUG: KMSAN: uninit-value in neigh_dump_table net/core/neighbour.c:2348 [inline]
BUG: KMSAN: uninit-value in neigh_dump_info+0x1af0/0x2250 net/core/neighbour.c:2438
CPU: 1 PID: 3575 Comm: syzkaller268891 Not tainted 4.16.0+ #83
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+0x185/0x1d0 lib/dump_stack.c:53
kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
__msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
neigh_master_filtered net/core/neighbour.c:2292 [inline]
neigh_dump_table net/core/neighbour.c:2348 [inline]
neigh_dump_info+0x1af0/0x2250 net/core/neighbour.c:2438
netlink_dump+0x9ad/0x1540 net/netlink/af_netlink.c:2225
__netlink_dump_start+0x1167/0x12a0 net/netlink/af_netlink.c:2322
netlink_dump_start include/linux/netlink.h:214 [inline]
rtnetlink_rcv_msg+0x1435/0x1560 net/core/rtnetlink.c:4598
netlink_rcv_skb+0x355/0x5f0 net/netlink/af_netlink.c:2447
rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4653
netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
netlink_unicast+0x1672/0x1750 net/netlink/af_netlink.c:1337
netlink_sendmsg+0x1048/0x1310 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg net/socket.c:640 [inline]
___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
__sys_sendmsg net/socket.c:2080 [inline]
SYSC_sendmsg+0x2a3/0x3d0 net/socket.c:2091
SyS_sendmsg+0x54/0x80 net/socket.c:2087
do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x43fed9
RSP: 002b:00007ffddbee2798 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fed9
RDX: 0000000000000000 RSI: 0000000020005000 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 0000000000401800
R13: 0000000000401890 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321
slab_post_alloc_hook mm/slab.h:445 [inline]
slab_alloc_node mm/slub.c:2737 [inline]
__kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369
__kmalloc_reserve net/core/skbuff.c:138 [inline]
__alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
alloc_skb include/linux/skbuff.h:984 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1183 [inline]
netlink_sendmsg+0x9a6/0x1310 net/netlink/af_netlink.c:1875
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg net/socket.c:640 [inline]
___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
__sys_sendmsg net/socket.c:2080 [inline]
SYSC_sendmsg+0x2a3/0x3d0 net/socket.c:2091
SyS_sendmsg+0x54/0x80 net/socket.c:2087
do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Fixes: 21fdd092acc7 ("net: Add support for filtering neigh dump by master device")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Ahern <dsa@cumulusnetworks.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/neighbour.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2331,12 +2331,16 @@ static int neigh_dump_table(struct neigh

err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL, NULL);
if (!err) {
- if (tb[NDA_IFINDEX])
+ if (tb[NDA_IFINDEX]) {
+ if (nla_len(tb[NDA_IFINDEX]) != sizeof(u32))
+ return -EINVAL;
filter_idx = nla_get_u32(tb[NDA_IFINDEX]);
-
- if (tb[NDA_MASTER])
+ }
+ if (tb[NDA_MASTER]) {
+ if (nla_len(tb[NDA_MASTER]) != sizeof(u32))
+ return -EINVAL;
filter_master_idx = nla_get_u32(tb[NDA_MASTER]);
-
+ }
if (filter_idx || filter_master_idx)
flags |= NLM_F_DUMP_FILTERED;
}

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