linux-kernel - WARNING: kmalloc bug in __v9fs_get

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Date:   Tue, 10 Jul 2018 06:29:02 -0700
From:   syzbot <syzbot+6e438f4036df52cbb863@...kaller.appspotmail.com>
To:     ericvh@...il.com, linux-kernel@...r.kernel.org, lucho@...kov.net,
        rminnich@...dia.gov, syzkaller-bugs@...glegroups.com,
        v9fs-developer@...ts.sourceforge.net
Subject: WARNING: kmalloc bug in __v9fs_get_acl

Hello,

syzbot found the following crash on:

HEAD commit:    3951bd9fe3e2 Add linux-next specific files for 20180710
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11a281b2400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b6e8479ba596271a
dashboard link: https://syzkaller.appspot.com/bug?extid=6e438f4036df52cbb863
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10f7ca2c400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=104b1a2c400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6e438f4036df52cbb863@...kaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
WARNING: CPU: 0 PID: 4463 at mm/slab_common.c:1031 kmalloc_slab+0x56/0x70  
mm/slab_common.c:1031
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4463 Comm: syz-executor437 Not tainted  
4.18.0-rc4-next-20180710+ #3
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+0x1c9/0x2b4 lib/dump_stack.c:113
  panic+0x238/0x4e7 kernel/panic.c:184
  __warn.cold.8+0x163/0x1ba kernel/panic.c:536
  report_bug+0x252/0x2d0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:178 [inline]
  do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:996
RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:1031
Code: c5 c0 0a d2 88 5d c3 b8 10 00 00 00 48 85 ff 74 f4 83 ef 01 c1 ef 03  
0f b6 87 e0 09 d2 88 eb d8 31 c0 81 e6 00 02 00 00 75 db <0f> 0b 5d c3 48  
8b 04 c5 00 0a d2 88 5d c3 66 90 66 2e 0f 1f 84 00
RSP: 0018:ffff8801ac9bfa30 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000700000000 RCX: ffffffff82b10c44
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000700000000
RBP: ffff8801ac9bfa30 R08: ffff8801ace58100 R09: fffffbfff12569a8
R10: fffffbfff12569a8 R11: ffffffff892b4d43 R12: fffffffffffffff4
R13: ffff8801b30e5b80 R14: ffff8801b30e5b80 R15: 0000000000608040
  __do_kmalloc mm/slab.c:3713 [inline]
  __kmalloc+0x25/0x760 mm/slab.c:3727
  kmalloc include/linux/slab.h:518 [inline]
  kzalloc include/linux/slab.h:707 [inline]
  __v9fs_get_acl+0xc5/0x170 fs/9p/acl.c:36
  v9fs_get_acl+0xe5/0x2a0 fs/9p/acl.c:70
  v9fs_mount+0x64b/0x900 fs/9p/vfs_super.c:191
  legacy_get_tree+0x118/0x440 fs/fs_context.c:659
  vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
  do_new_mount fs/namespace.c:2567 [inline]
  do_mount+0x6c1/0x1fb0 fs/namespace.c:2889
  ksys_mount+0x12d/0x140 fs/namespace.c:3105
  __do_sys_mount fs/namespace.c:3119 [inline]
  __se_sys_mount fs/namespace.c:3116 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3116
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4404a9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffabc5f1b8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00000000004404a9
RDX: 0000000020000900 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 64663d736e617274 R08: 0000000020000540 R09: 00007fffabc5f338
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000401d30
R13: 0000000000401dc0 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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