net: nfc, x25: use-after-free in llcp_sock_release
From: Sasha Levin
Date: Sun Jan 10 2016 - 19:16:26 EST
Hi all,
While fuzzing with trinity inside a KVM tools guest, running the latest -next
kernel, I've hit the following use after free:
[ 1174.605592] BUG: KASAN: use-after-free in llcp_sock_release+0xd0/0x4d0 at addr ffff8801c7eb8d90
[ 1174.606558] Read of size 8 by task trinity-c91/16209
[ 1174.607125] =============================================================================
[ 1174.608041] BUG kmalloc-2048 (Not tainted): kasan: bad access detected
[ 1174.608812] -----------------------------------------------------------------------------
[ 1174.608812]
[ 1174.609877] Disabling lock debugging due to kernel taint
[ 1174.610522] INFO: Allocated in sk_prot_alloc+0x1bf/0x340 age=169 cpu=2 pid=16194
[ 1174.611515] ___slab_alloc+0x7e9/0x900
[ 1174.611962] __slab_alloc.isra.23+0xf9/0x170
[ 1174.612462] __kmalloc+0x21d/0x330
[ 1174.612861] sk_prot_alloc+0x1bf/0x340
[ 1174.613294] sk_alloc+0xc0/0xd30
[ 1174.613699] x25_alloc_socket+0x2e/0x340
[ 1174.614151] x25_create+0xb1/0x4b0
[ 1174.614623] __sock_create+0x419/0x680
[ 1174.615059] SyS_socket+0x18e/0x220
[ 1174.615488] entry_SYSCALL_64_fastpath+0x16/0x7a
[ 1174.616033] INFO: Freed in sk_destruct+0x531/0x5b0 age=15 cpu=2 pid=16205
[ 1174.616795] __slab_free+0x8b/0x300
[ 1174.617202] kfree+0x2a5/0x2e0
[ 1174.617572] sk_destruct+0x531/0x5b0
[ 1174.617987] __sk_free+0x19d/0x210
[ 1174.618388] sk_free+0x30/0x40
[ 1174.618751] x25_release+0x2b1/0x2c0
[ 1174.619167] sock_release+0xac/0x1f0
[ 1174.619603] sock_close+0x16/0x20
[ 1174.620004] __fput+0x396/0x710
[ 1174.620380] ____fput+0x15/0x20
[ 1174.620766] task_work_run+0x1b5/0x1f0
[ 1174.621352] do_exit+0xec2/0x1570
[ 1174.621752] do_group_exit+0x1fb/0x330
[ 1174.622191] get_signal+0x1610/0x1890
[ 1174.622635] do_signal+0x8d/0x1ef0
[ 1174.623042] exit_to_usermode_loop+0xb1/0x210
[ 1174.623564] INFO: Slab 0xffffea00071fae00 objects=13 used=10 fp=0xffff8801c7ebef00 flags=0x2fffff80004080
[ 1174.624609] INFO: Object 0xffff8801c7eb8940 @offset=2368 fp=0x (null)
[ 1174.624609]
[ 1174.625582] Bytes b4 ffff8801c7eb8930: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.626627] Object ffff8801c7eb8940: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.627668] Object ffff8801c7eb8950: 09 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............
[ 1174.628695] Object ffff8801c7eb8960: 00 00 00 00 00 00 00 00 80 1d b0 b8 ff ff ff ff ................
[ 1174.630142] Object ffff8801c7eb8970: 40 8c 05 b8 ff ff ff ff 00 00 00 00 00 00 00 00 @...............
[ 1174.631605] Object ffff8801c7eb8980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.632788] Object ffff8801c7eb8990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.633815] Object ffff8801c7eb89a0: 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.634839] Object ffff8801c7eb89b0: 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.635881] Object ffff8801c7eb89c0: 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
[ 1174.636962] Object ffff8801c7eb89d0: ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.637985] Object ffff8801c7eb89e0: c8 5e c1 bb ff ff ff ff f0 f0 22 ba ff ff ff ff .^........".....
[ 1174.639007] Object ffff8801c7eb89f0: 00 00 00 00 00 00 00 00 a0 f7 81 ab ff ff ff ff ................
[ 1174.640045] Object ffff8801c7eb8a00: 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
[ 1174.641068] Object ffff8801c7eb8a10: ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.642218] Object ffff8801c7eb8a20: c0 5b c1 bb ff ff ff ff 00 00 00 00 00 00 00 00 .[..............
[ 1174.643244] Object ffff8801c7eb8a30: 00 00 00 00 00 00 00 00 c0 dd 81 ab ff ff ff ff ................
[ 1174.644328] Object ffff8801c7eb8a40: 40 8a eb c7 01 88 ff ff 40 8a eb c7 01 88 ff ff @.......@.......
[ 1174.645358] Object ffff8801c7eb8a50: 48 60 c1 bb ff ff ff ff a0 f2 22 ba ff ff ff ff H`........".....
[ 1174.646380] Object ffff8801c7eb8a60: 00 00 00 00 00 00 00 00 a0 03 82 ab ff ff ff ff ................
[ 1174.647407] Object ffff8801c7eb8a70: 70 8a eb c7 01 88 ff ff 70 8a eb c7 01 88 ff ff p.......p.......
[ 1174.648447] Object ffff8801c7eb8a80: 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
[ 1174.649466] Object ffff8801c7eb8a90: ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.650490] Object ffff8801c7eb8aa0: 00 5b c1 bb ff ff ff ff 20 28 22 ba ff ff ff ff .[...... (".....
[ 1174.651645] Object ffff8801c7eb8ab0: 00 00 00 00 00 00 00 00 60 d4 81 ab ff ff ff ff ........`.......
[ 1174.652669] Object ffff8801c7eb8ac0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.653700] Object ffff8801c7eb8ad0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.654721] Object ffff8801c7eb8ae0: 00 00 00 00 00 00 00 00 00 00 00 00 00 40 03 00 .............@..
[ 1174.655755] Object ffff8801c7eb8af0: 00 00 00 00 00 00 00 00 c0 08 6d c7 01 88 ff ff ..........m.....
[ 1174.656777] Object ffff8801c7eb8b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.657802] Object ffff8801c7eb8b10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.658823] Object ffff8801c7eb8b20: 00 00 00 00 00 00 00 00 00 40 03 00 00 00 00 00 .........@......
[ 1174.659856] Object ffff8801c7eb8b30: 30 8b eb c7 01 88 ff ff 30 8b eb c7 01 88 ff ff 0.......0.......
[ 1174.660879] Object ffff8801c7eb8b40: 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
[ 1174.662035] Object ffff8801c7eb8b50: ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.663058] Object ffff8801c7eb8b60: 00 5b c1 bb ff ff ff ff 20 28 22 ba ff ff ff ff .[...... (".....
[ 1174.664101] Object ffff8801c7eb8b70: 00 00 00 00 00 00 00 00 60 d4 81 ab ff ff ff ff ........`.......
[ 1174.665123] Object ffff8801c7eb8b80: 02 00 05 00 00 00 00 00 c0 00 40 02 ff ff ff ff ..........@.....
[ 1174.666145] Object ffff8801c7eb8b90: ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.667166] Object ffff8801c7eb8ba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.668211] Object ffff8801c7eb8bb0: 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.669239] Object ffff8801c7eb8bc0: c0 8b eb c7 01 88 ff ff c0 8b eb c7 01 88 ff ff ................
[ 1174.670262] Object ffff8801c7eb8bd0: 00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de .............N..
[ 1174.671410] Object ffff8801c7eb8be0: ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
[ 1174.672444] Object ffff8801c7eb8bf0: 00 5b c1 bb ff ff ff ff 00 00 00 00 00 00 00 00 .[..............
[ 1174.673465] Object ffff8801c7eb8c00: 00 00 00 00 00 00 00 00 60 d4 81 ab ff ff ff ff ........`.......
[ 1174.674485] Object ffff8801c7eb8c10: 80 1d b0 b8 ff ff ff ff 00 00 00 00 00 00 00 00 ................
[ 1174.675516] Object ffff8801c7eb8c20: ed 1e af de ff ff ff ff ff ff ff ff ff ff ff ff ................
[ 1174.676543] Object ffff8801c7eb8c30: 48 5d c1 bb ff ff ff ff 00 00 00 00 00 00 00 00 H]..............
[ 1174.677565] Object ffff8801c7eb8c40: 00 00 00 00 00 00 00 00 a0 eb 81 ab ff ff ff ff ................
[ 1174.678583] Object ffff8801c7eb8c50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.679621] Object ffff8801c7eb8c60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.680644] Object ffff8801c7eb8c70: 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff 7f ................
[ 1174.681787] Object ffff8801c7eb8c80: ff ff ff ff ff ff ff 7f 00 00 00 00 00 00 00 00 ................
[ 1174.682811] Object ffff8801c7eb8c90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.683849] Object ffff8801c7eb8ca0: d0 68 03 a9 ff ff ff ff 40 89 eb c7 01 88 ff ff .h......@.......
[ 1174.684874] Object ffff8801c7eb8cb0: 02 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 ................
[ 1174.685900] Object ffff8801c7eb8cc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.686925] Object ffff8801c7eb8cd0: 00 00 00 00 00 00 00 00 c0 5a c1 bb ff ff ff ff .........Z......
[ 1174.687964] Object ffff8801c7eb8ce0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.688993] Object ffff8801c7eb8cf0: a0 d4 81 ab ff ff ff ff 00 36 65 c4 ff ff ff ff .........6e.....
[ 1174.690015] Object ffff8801c7eb8d00: 00 00 00 00 00 00 00 00 00 5a 22 d2 01 88 ff ff .........Z".....
[ 1174.691041] Object ffff8801c7eb8d10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.692197] Object ffff8801c7eb8d20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.693229] Object ffff8801c7eb8d30: ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.694255] Object ffff8801c7eb8d40: 30 24 94 ba ff ff ff ff 00 00 00 00 00 00 00 00 0$..............
[ 1174.695276] Object ffff8801c7eb8d50: b0 c4 62 a8 ff ff ff ff 20 c7 62 a8 ff ff ff ff ..b..... .b.....
[ 1174.696314] Object ffff8801c7eb8d60: b0 e0 62 a8 ff ff ff ff d0 cb 62 a8 ff ff ff ff ..b.......b.....
[ 1174.697341] Object ffff8801c7eb8d70: b0 0f 03 a9 ff ff ff ff 70 32 62 a8 ff ff ff ff ........p2b.....
[ 1174.698369] Object ffff8801c7eb8d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.699395] Object ffff8801c7eb8d90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.700434] Object ffff8801c7eb8da0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.701582] Object ffff8801c7eb8db0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.702603] Object ffff8801c7eb8dc0: 00 00 00 00 00 00 00 00 b8 0b 00 00 00 00 00 00 ................
[ 1174.703640] Object ffff8801c7eb8dd0: 40 0d 03 00 00 00 00 00 20 bf 02 00 00 00 00 00 @....... .......
[ 1174.704665] Object ffff8801c7eb8de0: 20 bf 02 00 00 00 00 00 00 00 00 00 00 00 00 00 ...............
[ 1174.705689] Object ffff8801c7eb8df0: 04 00 00 00 00 00 00 00 f8 8d eb c7 01 88 ff ff ................
[ 1174.706712] Object ffff8801c7eb8e00: f8 8d eb c7 01 88 ff ff 00 00 00 00 00 00 00 00 ................
[ 1174.707751] Object ffff8801c7eb8e10: 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
[ 1174.708772] Object ffff8801c7eb8e20: ff ff ff ff ff ff ff ff c0 7d c5 bb ff ff ff ff .........}......
[ 1174.709792] Object ffff8801c7eb8e30: 50 f4 22 ba ff ff ff ff 00 00 00 00 00 00 00 00 P.".............
[ 1174.710813] Object ffff8801c7eb8e40: c0 c8 90 ab ff ff ff ff 48 8e eb c7 01 88 ff ff ........H.......
[ 1174.711973] Object ffff8801c7eb8e50: 48 8e eb c7 01 88 ff ff 00 00 00 00 00 00 00 00 H...............
[ 1174.712997] Object ffff8801c7eb8e60: 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
[ 1174.714017] Object ffff8801c7eb8e70: ff ff ff ff ff ff ff ff c0 7d c5 bb ff ff ff ff .........}......
[ 1174.715041] Object ffff8801c7eb8e80: 50 f4 22 ba ff ff ff ff 00 00 00 00 00 00 00 00 P.".............
[ 1174.716078] Object ffff8801c7eb8e90: c0 c8 90 ab ff ff ff ff 98 8e eb c7 01 88 ff ff ................
[ 1174.717099] Object ffff8801c7eb8ea0: 98 8e eb c7 01 88 ff ff 00 00 00 00 00 00 00 00 ................
[ 1174.718122] Object ffff8801c7eb8eb0: 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
[ 1174.719143] Object ffff8801c7eb8ec0: ff ff ff ff ff ff ff ff c0 7d c5 bb ff ff ff ff .........}......
[ 1174.720941] Object ffff8801c7eb8ed0: 50 f4 22 ba ff ff ff ff 00 00 00 00 00 00 00 00 P.".............
[ 1174.722084] Object ffff8801c7eb8ee0: c0 c8 90 ab ff ff ff ff e8 8e eb c7 01 88 ff ff ................
[ 1174.723108] Object ffff8801c7eb8ef0: e8 8e eb c7 01 88 ff ff 00 00 00 00 00 00 00 00 ................
[ 1174.724149] Object ffff8801c7eb8f00: 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
[ 1174.725172] Object ffff8801c7eb8f10: ff ff ff ff ff ff ff ff c0 7d c5 bb ff ff ff ff .........}......
[ 1174.726198] Object ffff8801c7eb8f20: 50 f4 22 ba ff ff ff ff 00 00 00 00 00 00 00 00 P.".............
[ 1174.727223] Object ffff8801c7eb8f30: c0 c8 90 ab ff ff ff ff 00 00 00 00 00 00 00 00 ................
[ 1174.729182] Object ffff8801c7eb8f40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.730209] Object ffff8801c7eb8f50: b0 6a 03 a9 ff ff ff ff 40 89 eb c7 01 88 ff ff .j......@.......
[ 1174.731357] Object ffff8801c7eb8f60: 02 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 ................
[ 1174.732396] Object ffff8801c7eb8f70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.733422] Object ffff8801c7eb8f80: 00 00 00 00 00 00 00 00 00 7f c5 bb ff ff ff ff ................
[ 1174.734452] Object ffff8801c7eb8f90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.735474] Object ffff8801c7eb8fa0: 20 ea 90 ab ff ff ff ff 00 00 00 00 02 00 00 00 ...............
[ 1174.736513] Object ffff8801c7eb8fb0: 02 00 00 00 07 00 00 00 07 00 00 00 00 00 00 00 ................
[ 1174.737538] Object ffff8801c7eb8fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.738559] Object ffff8801c7eb8fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.739599] Object ffff8801c7eb8fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.740621] Object ffff8801c7eb8ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.741765] Object ffff8801c7eb9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.742792] Object ffff8801c7eb9010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.743829] Object ffff8801c7eb9020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.744853] Object ffff8801c7eb9030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.745874] Object ffff8801c7eb9040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.746895] Object ffff8801c7eb9050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.747934] Object ffff8801c7eb9060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.748955] Object ffff8801c7eb9070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.749978] Object ffff8801c7eb9080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.751002] Object ffff8801c7eb9090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.752185] Object ffff8801c7eb90a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.753211] Object ffff8801c7eb90b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.754234] Object ffff8801c7eb90c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.755257] Object ffff8801c7eb90d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.756292] Object ffff8801c7eb90e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.757319] Object ffff8801c7eb90f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.758340] Object ffff8801c7eb9100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.759363] Object ffff8801c7eb9110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.760401] Object ffff8801c7eb9120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.761555] Object ffff8801c7eb9130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 1174.762578] Redzone ffff8801c7eb9140: bb bb bb bb bb bb bb bb ........
[ 1174.763553] Padding ffff8801c7eb9278: 00 00 00 00 00 00 00 00 ........
[ 1174.764527] CPU: 0 PID: 16209 Comm: trinity-c91 Tainted: G B 4.4.0-rc8-next-20160108-sasha-00024-gaaecb9a #2780
[ 1174.765773] 1ffff10018853ef0 00000000442a53ff ffff8800c429f800 ffffffffa101a182
[ 1174.766701] 0000000041b58ab3 ffffffffac1b3838 ffffffffa101a0b7 ffff8800c1888000
[ 1174.767637] ffffffffac1d02b7 ffff8801d2404d80 0000000000000008 ffff8801c7eb8940
[ 1174.768559] Call Trace:
[ 1174.768895] dump_stack (lib/dump_stack.c:52)
[ 1174.770831] print_trailer (mm/slub.c:655)
[ 1174.771610] object_err (mm/slub.c:662)
[ 1174.772193] kasan_report_error (mm/kasan/report.c:138 mm/kasan/report.c:236)
[ 1174.774893] __asan_report_load8_noabort (mm/kasan/report.c:280)
[ 1174.776390] llcp_sock_release (net/nfc/llcp_sock.c:594)
[ 1174.778349] sock_release (net/socket.c:573)
[ 1174.778963] sock_close (net/socket.c:1025)
[ 1174.779570] __fput (fs/file_table.c:209)
[ 1174.780135] ____fput (fs/file_table.c:245)
[ 1174.780711] task_work_run (kernel/task_work.c:117 (discriminator 1))
[ 1174.781516] do_exit (kernel/exit.c:749)
[ 1174.784891] do_group_exit (kernel/exit.c:862)
[ 1174.785527] get_signal (kernel/signal.c:2307)
[ 1174.786147] do_signal (arch/x86/kernel/signal.c:781)
[ 1174.791847] exit_to_usermode_loop (arch/x86/entry/common.c:249)
[ 1174.792552] syscall_return_slowpath (./arch/x86/include/asm/jump_label.h:35 include/linux/context_tracking_state.h:30 include/linux/context_tracking.h:24 arch/x86/entry/common.c:284 arch/x86/entry/common.c:344)
[ 1174.793274] int_ret_from_sys_call (arch/x86/entry/entry_64.S:282)
[ 1174.793958] Memory state around the buggy address:
[ 1174.794511] ffff8801c7eb8c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1174.795306] ffff8801c7eb8d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1174.796125] >ffff8801c7eb8d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1174.796925] ^
[ 1174.797358] ffff8801c7eb8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1174.798160] ffff8801c7eb8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb