linux-kernel - [syzbot] BUG: unable to handle kernel NULL pointer dereference in tiocsti

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Message-ID: <000000000000e12a9005e6ff4417@google.com>
Date:   Wed, 24 Aug 2022 09:35:30 -0700
From:   syzbot <syzbot+032314e8d7de2bdb97f7@...kaller.appspotmail.com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] BUG: unable to handle kernel NULL pointer dereference in tiocsti

Hello,

syzbot found the following issue on:

HEAD commit:    1c23f9e627a7 Linux 6.0-rc2
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17eefdcb080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3045c937aad027f7
dashboard link: https://syzkaller.appspot.com/bug?extid=032314e8d7de2bdb97f7
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1190eb6b080000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16a1e50d080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+032314e8d7de2bdb97f7@...kaller.appspotmail.com

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
  ESR = 0x0000000086000006
  EC = 0x21: IABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=000000010b28b000
[0000000000000000] pgd=080000010b411003, p4d=080000010b411003, pud=080000010b47b003, pmd=0000000000000000
Internal error: Oops: 86000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 3028 Comm: syz-executor908 Not tainted 6.0.0-rc2-syzkaller-16440-g1c23f9e627a7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/20/2022
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : 0x0
lr : gsmld_receive_buf+0x140/0x214 drivers/tty/n_gsm.c:2861
sp : ffff80000ffe3cb0
x29: ffff80000ffe3cc0 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: ffff80000d937000
x23: ffff80000d681e40 x22: ffff0000cb2dc000 x21: ffff80000ffe3d21
x20: ffff80000c205988 x19: ffff80000ffe3d24 x18: 00000000000000c0
x17: ffff80000dd7a698 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000004 x12: ffff80000d681e78
x11: ff808000098e7e04 x10: 0000000000000000 x9 : ffff8000098e7e04
x8 : 0000000000000000 x7 : ffff8000098dcea4 x6 : 0000000000000000
x5 : ffff80000e087890 x4 : 0000000000000002 x3 : 0000000000000001
x2 : ffff80000ffe3d20 x1 : 0000000000000000 x0 : ffff0000cb2dc000
Call trace:
 0x0
 tiocsti+0x168/0x1c4 drivers/tty/tty_io.c:2293
 tty_ioctl+0x284/0x9f4 drivers/tty/tty_io.c:2692
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
Code: bad PC value
---[ end trace 0000000000000000 ]---


---
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