Re: [PATCH net-next v4] skb_expand_head() adjust skb->truesize incorrectly
From: Christoph Paasch
Date: Wed Sep 01 2021 - 12:58:47 EST
Hello,
On Wed, Sep 1, 2021 at 1:12 AM Vasily Averin <vvs@xxxxxxxxxxxxx> wrote:
>
> Christoph Paasch reports [1] about incorrect skb->truesize
> after skb_expand_head() call in ip6_xmit.
> This may happen because of two reasons:
> - skb_set_owner_w() for newly cloned skb is called too early,
> before pskb_expand_head() where truesize is adjusted for (!skb-sk) case.
> - pskb_expand_head() does not adjust truesize in (skb->sk) case.
> In this case sk->sk_wmem_alloc should be adjusted too.
>
> [1] https://lkml.org/lkml/2021/8/20/1082
>
> Fixes: f1260ff15a71 ("skbuff: introduce skb_expand_head()")
> Reported-by: Christoph Paasch <christoph.paasch@xxxxxxxxx>
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
> ---
> v4: decided to use is_skb_wmem() after pskb_expand_head() call
> fixed 'return (EXPRESSION);' in os_skb_wmem according to Eric Dumazet
> v3: removed __pskb_expand_head(),
> added is_skb_wmem() helper for skb with wmem-compatible destructors
> there are 2 ways to use it:
> - before pskb_expand_head(), to create skb clones
> - after successfull pskb_expand_head() to change owner on extended skb.
> v2: based on patch version from Eric Dumazet,
> added __pskb_expand_head() function, which can be forced
> to adjust skb->truesize and sk->sk_wmem_alloc.
> ---
> include/net/sock.h | 1 +
> net/core/skbuff.c | 35 ++++++++++++++++++++++++++---------
> net/core/sock.c | 8 ++++++++
> 3 files changed, 35 insertions(+), 9 deletions(-)
this introduces more issues with the syzkaller reproducer that I
shared earlier (see below for the output).
I don't have time at the moment to dig into these though - so just
sharing this as an FYI for now.
syzkaller login: [ 12.768064] cgroup: Unknown subsys name 'perf_event'
[ 12.769831] cgroup: Unknown subsys name 'net_cls'
[ 13.587819] ------------[ cut here ]------------
[ 13.588943] refcount_t: saturated; leaking memory.
[ 13.590166] WARNING: CPU: 1 PID: 1658 at lib/refcount.c:22
refcount_warn_saturate+0xce/0x1f0
[ 13.591909] Modules linked in:
[ 13.592595] CPU: 1 PID: 1658 Comm: syz-executor Not tainted
5.14.0ea78abdd8ff18baaea3211eabdd6a2a88169cfd6 #134
[ 13.594455] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 13.596640] RIP: 0010:refcount_warn_saturate+0xce/0x1f0
[ 13.597651] Code: 1d 32 63 11 02 31 ff 89 de e8 1e 26 79 ff 84 db
75 d8 e8 b5 1e 79 ff 48 c7 c7 80 48 32 83 c6 05 12 63 11 02 01 e8 2f
39
[ 13.601049] RSP: 0018:ffffc9000091f2a8 EFLAGS: 00010286
[ 13.602077] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 13.603477] RDX: ffff888100fa2880 RSI: ffffffff8121e533 RDI: fffff52000123e47
[ 13.604758] RBP: ffff88810b88013c R08: 0000000000000001 R09: 0000000000000000
[ 13.606110] R10: ffffffff814135db R11: 0000000000000000 R12: ffff88810b880000
[ 13.607421] R13: 00000000fffffe03 R14: ffff8881094c97c0 R15: ffff88810b88013c
[ 13.608874] FS: 00007f8ad457d700(0000) GS:ffff88811b480000(0000)
knlGS:0000000000000000
[ 13.610515] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 13.611671] CR2: 0000000000000000 CR3: 00000001045d8000 CR4: 00000000000006e0
[ 13.613017] Call Trace:
[ 13.613521] skb_expand_head+0x35a/0x470
[ 13.614331] ip6_xmit+0x105f/0x1560
[ 13.615038] ? ip6_forward+0x22b0/0x22b0
[ 13.616011] ? ip6_dst_check+0x227/0x540
[ 13.616773] ? rt6_check_expired+0x250/0x250
[ 13.617657] ? __sk_dst_check+0xfb/0x200
[ 13.618424] ? inet6_csk_route_socket+0x59e/0x980
[ 13.619377] ? inet6_csk_addr2sockaddr+0x2a0/0x2a0
[ 13.620399] ? stack_trace_consume_entry+0x160/0x160
[ 13.621530] inet6_csk_xmit+0x2b3/0x430
[ 13.622290] ? kasan_save_stack+0x32/0x40
[ 13.623133] ? kasan_save_stack+0x1b/0x40
[ 13.623939] ? inet6_csk_route_socket+0x980/0x980
[ 13.624802] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 13.625786] ? csum_ipv6_magic+0x26/0x70
[ 13.626653] ? inet6_csk_route_socket+0x980/0x980
[ 13.627480] __tcp_transmit_skb+0x186e/0x35d0
[ 13.628358] ? __tcp_select_window+0xa50/0xa50
[ 13.629153] ? __sanitizer_cov_trace_cmp4+0x1c/0x70
[ 13.630130] ? kasan_unpoison+0x23/0x50
[ 13.630872] ? __build_skb_around+0x241/0x300
[ 13.631667] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.632785] ? __alloc_skb+0x180/0x360
[ 13.633545] __tcp_send_ack.part.0+0x3da/0x650
[ 13.634333] tcp_send_ack+0x7d/0xa0
[ 13.635031] __tcp_ack_snd_check+0x156/0x8c0
[ 13.635957] tcp_rcv_established+0x1733/0x1d30
[ 13.636889] ? tcp_data_queue+0x4af0/0x4af0
[ 13.637753] tcp_v6_do_rcv+0x438/0x1380
[ 13.638523] __release_sock+0x1ad/0x310
[ 13.639306] release_sock+0x54/0x1a0
[ 13.640029] ? tcp_sendmsg_locked+0x2ee0/0x2ee0
[ 13.640953] tcp_sendmsg+0x36/0x40
[ 13.641710] inet6_sendmsg+0xb5/0x140
[ 13.642359] ? inet6_ioctl+0x2a0/0x2a0
[ 13.643092] ____sys_sendmsg+0x3b5/0x970
[ 13.643834] ? sock_release+0x1b0/0x1b0
[ 13.644593] ? __ia32_sys_recvmmsg+0x290/0x290
[ 13.645505] ? futex_wait_setup+0x2e0/0x2e0
[ 13.646350] ___sys_sendmsg+0xff/0x170
[ 13.647084] ? hash_futex+0x12/0x1f0
[ 13.647870] ? sendmsg_copy_msghdr+0x160/0x160
[ 13.648691] ? asm_exc_page_fault+0x1e/0x30
[ 13.649475] ? __sanitizer_cov_trace_const_cmp1+0x22/0x80
[ 13.650523] ? __fget_files+0x1c2/0x2a0
[ 13.651245] ? __fget_light+0xea/0x270
[ 13.652027] ? sockfd_lookup_light+0xc3/0x170
[ 13.652845] __sys_sendmmsg+0x192/0x440
[ 13.653622] ? __ia32_sys_sendmsg+0xb0/0xb0
[ 13.654365] ? vfs_fileattr_set+0xb80/0xb80
[ 13.655085] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.656175] ? alloc_file_pseudo+0x1/0x250
[ 13.657026] ? sock_ioctl+0x1bb/0x670
[ 13.657861] ? __do_sys_futex+0xe7/0x3d0
[ 13.658697] ? __do_sys_futex+0xe7/0x3d0
[ 13.659379] ? __do_sys_futex+0xf0/0x3d0
[ 13.660090] ? __restore_fpregs_from_fpstate+0xa9/0xf0
[ 13.661212] ? fpregs_mark_activate+0x130/0x130
[ 13.662078] ? do_futex+0x1be0/0x1be0
[ 13.662846] __x64_sys_sendmmsg+0x98/0x100
[ 13.663706] ? syscall_exit_to_user_mode+0x1d/0x40
[ 13.664698] do_syscall_64+0x3b/0x90
[ 13.665450] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 13.666564] RIP: 0033:0x7f8ad3e8c469
[ 13.667204] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40
00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24
08
[ 13.670776] RSP: 002b:00007f8ad457cda8 EFLAGS: 00000246 ORIG_RAX:
0000000000000133
[ 13.672208] RAX: ffffffffffffffda RBX: 0000000000000133 RCX: 00007f8ad3e8c469
[ 13.673598] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003
[ 13.674946] RBP: 0000000000000133 R08: 0000000000000000 R09: 0000000000000000
[ 13.676397] R10: 0000000040044040 R11: 0000000000000246 R12: 000000000069bf8c
[ 13.677876] R13: 00007ffe38506fef R14: 00007f8ad455d000 R15: 0000000000000003
[ 13.679129] ---[ end trace 55e20198e13af26c ]---
[ 13.680043] ------------[ cut here ]------------
[ 13.681049] refcount_t: underflow; use-after-free.
[ 13.682005] WARNING: CPU: 1 PID: 1658 at lib/refcount.c:28
refcount_warn_saturate+0x103/0x1f0
[ 13.683658] Modules linked in:
[ 13.684246] CPU: 1 PID: 1658 Comm: syz-executor Tainted: G W
5.14.0ea78abdd8ff18baaea3211eabdd6a2a88169cfd6 #134
[ 13.686321] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 13.688388] RIP: 0010:refcount_warn_saturate+0x103/0x1f0
[ 13.689502] Code: 1d fb 62 11 02 31 ff 89 de e8 e9 25 79 ff 84 db
75 a3 e8 80 1e 79 ff 48 c7 c7 80 49 32 83 c6 05 db 62 11 02 01 e8 fa
34
[ 13.692805] RSP: 0018:ffffc9000091eff8 EFLAGS: 00010286
[ 13.693756] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 13.695193] RDX: ffff888100fa2880 RSI: ffffffff8121e533 RDI: fffff52000123df1
[ 13.696696] RBP: ffff88810b88013c R08: 0000000000000001 R09: 0000000000000000
[ 13.697982] R10: ffffffff814135db R11: 0000000000000000 R12: ffff88810b88013c
[ 13.699291] R13: 00000000fffffe02 R14: ffff8881011a4c00 R15: ffff8881094c97c0
[ 13.700576] FS: 00007f8ad457d700(0000) GS:ffff88811b480000(0000)
knlGS:0000000000000000
[ 13.702031] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 13.703134] CR2: 0000000000000000 CR3: 00000001045d8000 CR4: 00000000000006e0
[ 13.704525] Call Trace:
[ 13.704973] __sock_wfree+0xec/0x110
[ 13.705737] ? sock_wfree+0x240/0x240
[ 13.706406] loopback_xmit+0x126/0x4b0
[ 13.707278] ? refcount_warn_saturate+0xce/0x1f0
[ 13.708208] dev_hard_start_xmit+0x16c/0x5c0
[ 13.709116] __dev_queue_xmit+0x1679/0x2970
[ 13.709912] ? netdev_core_pick_tx+0x2d0/0x2d0
[ 13.710758] ? __sanitizer_cov_trace_const_cmp8+0x1d/0x70
[ 13.711846] ? report_bug+0x38/0x210
[ 13.712656] ? handle_bug+0x3c/0x60
[ 13.713395] ? exc_invalid_op+0x14/0x40
[ 13.714119] ip6_finish_output2+0xb52/0x14c0
[ 13.715029] ip6_output+0x572/0x9e0
[ 13.715761] ? ip6_fragment+0x1f40/0x1f40
[ 13.716478] ip6_xmit+0xc6f/0x1560
[ 13.717083] ? ip6_forward+0x22b0/0x22b0
[ 13.717895] ? ip6_dst_check+0x227/0x540
[ 13.718689] ? rt6_check_expired+0x250/0x250
[ 13.719620] ? __sk_dst_check+0xfb/0x200
[ 13.720427] ? inet6_csk_route_socket+0x59e/0x980
[ 13.721408] ? inet6_csk_addr2sockaddr+0x2a0/0x2a0
[ 13.722286] ? stack_trace_consume_entry+0x160/0x160
[ 13.723186] inet6_csk_xmit+0x2b3/0x430
[ 13.723873] ? kasan_save_stack+0x32/0x40
[ 13.724682] ? kasan_save_stack+0x1b/0x40
[ 13.725422] ? inet6_csk_route_socket+0x980/0x980
[ 13.726398] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 13.727478] ? csum_ipv6_magic+0x26/0x70
[ 13.728288] ? inet6_csk_route_socket+0x980/0x980
[ 13.729267] __tcp_transmit_skb+0x186e/0x35d0
[ 13.730048] ? __tcp_select_window+0xa50/0xa50
[ 13.730952] ? __sanitizer_cov_trace_cmp4+0x1c/0x70
[ 13.732007] ? kasan_unpoison+0x23/0x50
[ 13.732740] ? __build_skb_around+0x241/0x300
[ 13.733605] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.734749] ? __alloc_skb+0x180/0x360
[ 13.735506] __tcp_send_ack.part.0+0x3da/0x650
[ 13.736377] tcp_send_ack+0x7d/0xa0
[ 13.737015] __tcp_ack_snd_check+0x156/0x8c0
[ 13.737758] tcp_rcv_established+0x1733/0x1d30
[ 13.738679] ? tcp_data_queue+0x4af0/0x4af0
[ 13.739417] tcp_v6_do_rcv+0x438/0x1380
[ 13.740166] __release_sock+0x1ad/0x310
[ 13.740874] release_sock+0x54/0x1a0
[ 13.741527] ? tcp_sendmsg_locked+0x2ee0/0x2ee0
[ 13.742394] tcp_sendmsg+0x36/0x40
[ 13.743037] inet6_sendmsg+0xb5/0x140
[ 13.743752] ? inet6_ioctl+0x2a0/0x2a0
[ 13.744511] ____sys_sendmsg+0x3b5/0x970
[ 13.745325] ? sock_release+0x1b0/0x1b0
[ 13.746031] ? __ia32_sys_recvmmsg+0x290/0x290
[ 13.746914] ? futex_wait_setup+0x2e0/0x2e0
[ 13.747749] ___sys_sendmsg+0xff/0x170
[ 13.748393] ? hash_futex+0x12/0x1f0
[ 13.749036] ? sendmsg_copy_msghdr+0x160/0x160
[ 13.749972] ? asm_exc_page_fault+0x1e/0x30
[ 13.750870] ? __sanitizer_cov_trace_const_cmp1+0x22/0x80
[ 13.751974] ? __fget_files+0x1c2/0x2a0
[ 13.752659] ? __fget_light+0xea/0x270
[ 13.753514] ? sockfd_lookup_light+0xc3/0x170
[ 13.754296] __sys_sendmmsg+0x192/0x440
[ 13.755102] ? __ia32_sys_sendmsg+0xb0/0xb0
[ 13.755917] ? vfs_fileattr_set+0xb80/0xb80
[ 13.756692] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.757790] ? alloc_file_pseudo+0x1/0x250
[ 13.758675] ? sock_ioctl+0x1bb/0x670
[ 13.759341] ? __do_sys_futex+0xe7/0x3d0
[ 13.760040] ? __do_sys_futex+0xe7/0x3d0
[ 13.760762] ? __do_sys_futex+0xf0/0x3d0
[ 13.761585] ? __restore_fpregs_from_fpstate+0xa9/0xf0
[ 13.762511] ? fpregs_mark_activate+0x130/0x130
[ 13.763382] ? do_futex+0x1be0/0x1be0
[ 13.764044] __x64_sys_sendmmsg+0x98/0x100
[ 13.764831] ? syscall_exit_to_user_mode+0x1d/0x40
[ 13.765814] do_syscall_64+0x3b/0x90
[ 13.766607] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 13.767467] RIP: 0033:0x7f8ad3e8c469
[ 13.768206] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40
00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24
08
[ 13.771618] RSP: 002b:00007f8ad457cda8 EFLAGS: 00000246 ORIG_RAX:
0000000000000133
[ 13.773054] RAX: ffffffffffffffda RBX: 0000000000000133 RCX: 00007f8ad3e8c469
[ 13.774260] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003
[ 13.775586] RBP: 0000000000000133 R08: 0000000000000000 R09: 0000000000000000
[ 13.776909] R10: 0000000040044040 R11: 0000000000000246 R12: 000000000069bf8c
[ 13.778390] R13: 00007ffe38506fef R14: 00007f8ad455d000 R15: 0000000000000003
[ 13.779752] ---[ end trace 55e20198e13af26d ]---
[ 13.780935] ------------[ cut here ]------------
[ 13.781986] WARNING: CPU: 0 PID: 1658 at net/core/skbuff.c:5429
skb_try_coalesce+0x1019/0x12c0
[ 13.783740] Modules linked in:
[ 13.784398] CPU: 0 PID: 1658 Comm: syz-executor Tainted: G W
5.14.0ea78abdd8ff18baaea3211eabdd6a2a88169cfd6 #134
[ 13.786692] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 13.788958] RIP: 0010:skb_try_coalesce+0x1019/0x12c0
[ 13.789930] Code: 24 20 bf 01 00 00 00 8b 40 20 44 0f b7 f0 44 89
f6 e8 0b 2b cf fe 41 83 ee 01 0f 85 01 f3 ff ff e9 42 f6 ff ff e8 67
2c
[ 13.793371] RSP: 0018:ffffc9000091f530 EFLAGS: 00010293
[ 13.794316] RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
[ 13.795688] RDX: ffff888100fa2880 RSI: ffffffff826767a9 RDI: 0000000000000003
[ 13.797093] RBP: ffff888109496de0 R08: 0000000000000c00 R09: 0000000000000000
[ 13.798381] R10: ffffffff82676122 R11: 0000000000000000 R12: ffff888100efc0e0
[ 13.799766] R13: ffff8881046baac0 R14: 0000000000001000 R15: ffff888100efc156
[ 13.801052] FS: 00007f8ad457d700(0000) GS:ffff88811b400000(0000)
knlGS:0000000000000000
[ 13.802463] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 13.803603] CR2: 00007f83d8028000 CR3: 00000001045d8000 CR4: 00000000000006f0
[ 13.805079] Call Trace:
[ 13.805622] tcp_try_coalesce+0x312/0x870
[ 13.806488] ? tcp_ack_update_rtt+0xfc0/0xfc0
[ 13.807406] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.808483] ? tcp_try_rmem_schedule+0x99b/0x16e0
[ 13.809296] tcp_queue_rcv+0x73/0x670
[ 13.810013] tcp_data_queue+0x11e5/0x4af0
[ 13.810844] ? __sanitizer_cov_trace_const_cmp2+0x22/0x80
[ 13.811890] ? tcp_urg+0x108/0xb60
[ 13.812536] ? tcp_data_ready+0x550/0x550
[ 13.813362] ? tcp_enter_cwr+0x3f0/0x4d0
[ 13.814148] ? __sanitizer_cov_trace_cmp4+0x1c/0x70
[ 13.815014] ? ktime_get+0xf4/0x150
[ 13.815637] ? __sanitizer_cov_trace_const_cmp8+0x1d/0x70
[ 13.816721] tcp_rcv_established+0x83a/0x1d30
[ 13.817541] ? tcp_data_queue+0x4af0/0x4af0
[ 13.818375] tcp_v6_do_rcv+0x438/0x1380
[ 13.819160] __release_sock+0x1ad/0x310
[ 13.819975] release_sock+0x54/0x1a0
[ 13.820745] ? tcp_sendmsg_locked+0x2ee0/0x2ee0
[ 13.821662] tcp_sendmsg+0x36/0x40
[ 13.822351] inet6_sendmsg+0xb5/0x140
[ 13.823115] ? inet6_ioctl+0x2a0/0x2a0
[ 13.823909] ____sys_sendmsg+0x3b5/0x970
[ 13.824720] ? sock_release+0x1b0/0x1b0
[ 13.825521] ? __ia32_sys_recvmmsg+0x290/0x290
[ 13.826441] ? futex_wait_setup+0x2e0/0x2e0
[ 13.827308] ___sys_sendmsg+0xff/0x170
[ 13.828112] ? hash_futex+0x12/0x1f0
[ 13.828853] ? sendmsg_copy_msghdr+0x160/0x160
[ 13.829804] ? asm_exc_page_fault+0x1e/0x30
[ 13.830660] ? __sanitizer_cov_trace_const_cmp1+0x22/0x80
[ 13.831760] ? __fget_files+0x1c2/0x2a0
[ 13.832576] ? __fget_light+0xea/0x270
[ 13.833349] ? sockfd_lookup_light+0xc3/0x170
[ 13.834289] __sys_sendmmsg+0x192/0x440
[ 13.835065] ? __ia32_sys_sendmsg+0xb0/0xb0
[ 13.835918] ? vfs_fileattr_set+0xb80/0xb80
[ 13.836823] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[ 13.837941] ? alloc_file_pseudo+0x1/0x250
[ 13.838810] ? sock_ioctl+0x1bb/0x670
[ 13.839550] ? __do_sys_futex+0xe7/0x3d0
[ 13.840369] ? __do_sys_futex+0xe7/0x3d0
[ 13.841205] ? __do_sys_futex+0xf0/0x3d0
[ 13.842022] ? __restore_fpregs_from_fpstate+0xa9/0xf0
[ 13.843115] ? fpregs_mark_activate+0x130/0x130
[ 13.844074] ? do_futex+0x1be0/0x1be0
[ 13.844868] __x64_sys_sendmmsg+0x98/0x100
[ 13.845725] ? syscall_exit_to_user_mode+0x1d/0x40
[ 13.846754] do_syscall_64+0x3b/0x90
[ 13.847472] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 13.848550] RIP: 0033:0x7f8ad3e8c469
[ 13.849289] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40
00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24
08
[ 13.852935] RSP: 002b:00007f8ad457cda8 EFLAGS: 00000246 ORIG_RAX:
0000000000000133
[ 13.854476] RAX: ffffffffffffffda RBX: 0000000000000133 RCX: 00007f8ad3e8c469
[ 13.855896] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003
[ 13.857304] RBP: 0000000000000133 R08: 0000000000000000 R09: 0000000000000000
[ 13.858756] R10: 0000000040044040 R11: 0000000000000246 R12: 000000000069bf8c
[ 13.860168] R13: 00007ffe38506fef R14: 00007f8ad455d000 R15: 0000000000000003
[ 13.861597] ---[ end trace 55e20198e13af26e ]---
>
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 95b2577..173d58c 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1695,6 +1695,7 @@ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
> gfp_t priority);
> void __sock_wfree(struct sk_buff *skb);
> void sock_wfree(struct sk_buff *skb);
> +bool is_skb_wmem(const struct sk_buff *skb);
> struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size,
> gfp_t priority);
> void skb_orphan_partial(struct sk_buff *skb);
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index f931176..09991cb 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1804,28 +1804,45 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
> struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
> {
> int delta = headroom - skb_headroom(skb);
> + int osize = skb_end_offset(skb);
> + struct sk_buff *oskb = NULL;
> + struct sock *sk = skb->sk;
>
> if (WARN_ONCE(delta <= 0,
> "%s is expecting an increase in the headroom", __func__))
> return skb;
>
> - /* pskb_expand_head() might crash, if skb is shared */
> + delta = SKB_DATA_ALIGN(delta);
> + /* pskb_expand_head() might crash, if skb is shared.
> + * Also we should clone skb if its destructor does
> + * not adjust skb->truesize and sk->sk_wmem_alloc
> + */
> if (skb_shared(skb)) {
> struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
>
> - if (likely(nskb)) {
> - if (skb->sk)
> - skb_set_owner_w(nskb, skb->sk);
> - consume_skb(skb);
> - } else {
> + if (unlikely(!nskb)) {
> kfree_skb(skb);
> + return NULL;
> }
> + oskb = skb;
> skb = nskb;
> }
> - if (skb &&
> - pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
> + if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC)) {
> kfree_skb(skb);
> - skb = NULL;
> + kfree_skb(oskb);
> + return NULL;
> + }
> + if (oskb) {
> + if (sk)
> + skb_set_owner_w(skb, sk);
> + consume_skb(oskb);
> + } else if (sk) {
> + delta = osize - skb_end_offset(skb);
> + if (!is_skb_wmem(skb))
> + skb_set_owner_w(skb, sk);
> + skb->truesize += delta;
> + if (sk_fullsock(sk))
> + refcount_add(delta, &sk->sk_wmem_alloc);
> }
> return skb;
> }
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 950f1e7..6cbda43 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2227,6 +2227,14 @@ void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
> }
> EXPORT_SYMBOL(skb_set_owner_w);
>
> +bool is_skb_wmem(const struct sk_buff *skb)
> +{
> + return skb->destructor == sock_wfree ||
> + skb->destructor == __sock_wfree ||
> + (IS_ENABLED(CONFIG_INET) && skb->destructor == tcp_wfree);
> +}
> +EXPORT_SYMBOL(is_skb_wmem);
> +
> static bool can_skb_orphan_partial(const struct sk_buff *skb)
> {
> #ifdef CONFIG_TLS_DEVICE
> --
> 1.8.3.1
>