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| author | Eric Dumazet <edumazet@google.com> | 2018-05-10 19:07:13 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-05-11 12:29:42 -0400 |
| commit | 575b65bc5bff37ec502d5eab9fc91d0a8d5ec40e (patch) | |
| tree | ce7f8be003819645839d12d7dc0232db4d205b1a /net/ipv4/udp_offload.c | |
| parent | 73a6bab5aa2a83cb7df85805e08bc03b4065aea7 (diff) | |
| download | linux-575b65bc5bff37ec502d5eab9fc91d0a8d5ec40e.tar.bz2 | |
udp: avoid refcount_t saturation in __udp_gso_segment()
For some reason, Willem thought that the issue we fixed for TCP
in commit 7ec318feeed1 ("tcp: gso: avoid refcount_t warning from
tcp_gso_segment()") was not relevant for UDP GSO.
But syzbot found its way.
refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 10261 at lib/refcount.c:78 refcount_add_not_zero+0x2d4/0x320 lib/refcount.c:78
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 10261 Comm: syz-executor5 Not tainted 4.17.0-rc3+ #38
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
panic+0x22f/0x4de kernel/panic.c:184
__warn.cold.8+0x163/0x1b3 kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:refcount_add_not_zero+0x2d4/0x320 lib/refcount.c:78
RSP: 0018:ffff880196db6b90 EFLAGS: 00010282
RAX: 0000000000000026 RBX: 00000000ffffff01 RCX: ffffc900040d9000
RDX: 0000000000004a29 RSI: ffffffff8160f6f1 RDI: ffff880196db66f0
RBP: ffff880196db6c78 R08: ffff8801b33d6740 R09: 0000000000000002
R10: ffff8801b33d6740 R11: 0000000000000000 R12: 0000000000000000
R13: 00000000ffffffff R14: ffff880196db6c50 R15: 0000000000020101
refcount_add+0x1b/0x70 lib/refcount.c:102
__udp_gso_segment+0xaa5/0xee0 net/ipv4/udp_offload.c:272
udp4_ufo_fragment+0x592/0x7a0 net/ipv4/udp_offload.c:301
inet_gso_segment+0x639/0x12b0 net/ipv4/af_inet.c:1342
skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792
__skb_gso_segment+0x3bb/0x870 net/core/dev.c:2865
skb_gso_segment include/linux/netdevice.h:4050 [inline]
validate_xmit_skb+0x54d/0xd90 net/core/dev.c:3122
__dev_queue_xmit+0xbf8/0x34c0 net/core/dev.c:3579
dev_queue_xmit+0x17/0x20 net/core/dev.c:3620
neigh_direct_output+0x15/0x20 net/core/neighbour.c:1401
neigh_output include/net/neighbour.h:483 [inline]
ip_finish_output2+0xa5f/0x1840 net/ipv4/ip_output.c:229
ip_finish_output+0x828/0xf80 net/ipv4/ip_output.c:317
NF_HOOK_COND include/linux/netfilter.h:277 [inline]
ip_output+0x21b/0x850 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:444 [inline]
ip_local_out+0xc5/0x1b0 net/ipv4/ip_output.c:124
ip_send_skb+0x40/0xe0 net/ipv4/ip_output.c:1434
udp_send_skb.isra.37+0x5eb/0x1000 net/ipv4/udp.c:825
udp_push_pending_frames+0x5c/0xf0 net/ipv4/udp.c:853
udp_v6_push_pending_frames+0x380/0x3e0 net/ipv6/udp.c:1105
udp_lib_setsockopt+0x59a/0x600 net/ipv4/udp.c:2403
udpv6_setsockopt+0x95/0xa0 net/ipv6/udp.c:1447
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3046
__sys_setsockopt+0x1bd/0x390 net/socket.c:1903
__do_sys_setsockopt net/socket.c:1914 [inline]
__se_sys_setsockopt net/socket.c:1911 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: ad405857b174 ("udp: better wmem accounting on gso")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp_offload.c')
| -rw-r--r-- | net/ipv4/udp_offload.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index ede2a7305b90..92dc9e5a7ff3 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -268,9 +268,17 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0; /* update refcount for the packet */ - if (copy_dtor) - refcount_add(sum_truesize - gso_skb->truesize, - &sk->sk_wmem_alloc); + if (copy_dtor) { + int delta = sum_truesize - gso_skb->truesize; + + /* In some pathological cases, delta can be negative. + * We need to either use refcount_add() or refcount_sub_and_test() + */ + if (likely(delta >= 0)) + refcount_add(delta, &sk->sk_wmem_alloc); + else + WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc)); + } return segs; } EXPORT_SYMBOL_GPL(__udp_gso_segment); |