syzbot


BUG: unable to handle kernel paging request in slhc_free

Status: fixed on 2019/12/30 15:48
Reported-by: syzbot+12410819830704e2d4a1@syzkaller.appspotmail.com
Fix commit: da0bbf51bdcb slip: make slhc_free() silently accept an error pointer
First crash: 1393d, last: 1166d

Fix bisection: fixed by (bisect log) :
commit da0bbf51bdcb043fad034b6ccabc0775bd5397bc
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Apr 25 23:13:58 2019 +0000

  slip: make slhc_free() silently accept an error pointer

similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 BUG: unable to handle kernel paging request in slhc_free 1 1378d 1378d 0/1 auto-closed as invalid on 2019/10/25 08:43
upstream BUG: unable to handle kernel paging request in slhc_free C done done 177 1383d 1501d 17/24 fixed on 2020/03/11 20:34

Sample crash report:
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441129
RDX: 0000000020000100 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007ffe83f5f590 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000
BUG: unable to handle kernel paging request at fffffffffffffff4
IP: slhc_free+0x31/0xb0 drivers/net/slip/slhc.c:159
PGD 766d067 P4D 766d067 PUD 766f067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7230 Comm: syz-executor671 Not tainted 4.14.113 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888096928300 task.stack: ffff888083520000
RIP: 0010:slhc_free+0x31/0xb0 drivers/net/slip/slhc.c:159
RSP: 0018:ffff888083527ae8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: fffffffffffffff4 RCX: 1ffff11012d2517e
RDX: 1ffffffffffffffe RSI: ffff888096928bd0 RDI: fffffffffffffff4
RBP: ffff888083527af8 R08: ffff888096928300 R09: ffff888096928bf0
R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffff4
R13: ffff888096f29408 R14: ffff88809b977740 R15: ffff888096f28940
FS:  0000000001f5d880(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000000a5e44000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 sl_alloc_bufs drivers/net/slip/slip.c:197 [inline]
 slip_open+0xc96/0xfb5 drivers/net/slip/slip.c:826
 tty_ldisc_open.isra.0+0x75/0xc0 drivers/tty/tty_ldisc.c:474
 tty_set_ldisc+0x29a/0x610 drivers/tty/tty_ldisc.c:599
 tiocsetd drivers/tty/tty_io.c:2351 [inline]
 tty_ioctl+0x976/0x1340 drivers/tty/tty_io.c:2595
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7b9/0x1070 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441129
RSP: 002b:00007ffe83f5f578 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441129
RDX: 0000000020000100 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007ffe83f5f590 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000
Code: 41 54 49 89 fc e8 30 ee 87 fd 4d 85 e4 74 77 e8 26 ee 87 fd 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 6d <4d> 8b 2c 24 4d 85 ed 74 0d e8 01 ee 87 fd 4c 89 ef e8 69 69 b1 
RIP: slhc_free+0x31/0xb0 drivers/net/slip/slhc.c:159 RSP: ffff888083527ae8
CR2: fffffffffffffff4
---[ end trace 7795915591f4987e ]---

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-linux-4-14 2019/04/20 20:06 linux-4.14.y 68d7a45eec10 b0e8efcb .config console log report syz C
ci2-linux-4-14 2019/04/26 12:01 linux-4.14.y 68d7a45eec10 b617407b .config console log report
ci2-linux-4-14 2019/04/20 17:18 linux-4.14.y 68d7a45eec10 b0e8efcb .config console log report
ci2-linux-4-14 2019/04/16 06:59 linux-4.14.y 1ec8f1f0bffe 505ab413 .config console log report
* Struck through repros no longer work on HEAD.