BUG: unable to handle kernel NULL pointer dereference in kmem_cache_free (2)

[syzbot <syzbot+463e2f5d13fc785dd322@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    345671ea0f92 Merge branch 'akpm' (patches from Andrew)
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10442713400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c0a49d2b5210087
dashboard link: https://syzkaller.appspot.com/bug?extid=463e2f5d13fc785dd322
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+463e2f5d13fc785dd322@syzkaller.appspotmail.com

FAT-fs (loop1): Directory bread(block 72) failed
EXT4-fs (loop3): Can't read superblock on 2nd try
FAT-fs (loop1): Directory bread(block 73) failed
audit: type=1400 audit(1540684862.923:177): avc:  denied  { mmap_zero }  
for  pid=17455 comm="udevd" scontext=system_u:system_r:kernel_t:s0  
tcontext=system_u:system_r:kernel_t:s0 tclass=memprotect permissive=1
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 17455 Comm: udevd Not tainted 4.19.0+ #85
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:slab_equal_or_root mm/slab.h:228 [inline]
RIP: 0010:cache_from_obj mm/slab.h:374 [inline]
RIP: 0010:kmem_cache_free+0x120/0x290 mm/slab.c:3752
Code: ea ff ff 48 c1 e8 0c 48 c1 e0 06 48 01 d0 48 8b 50 08 48 8d 4a ff 83  
e2 01 48 0f 45 c1 48 8b 40 18 48 39 c3 0f 84 00 ff ff ff <48> 3b 98 80 00  
00 00 0f 84 11 01 00 00 48 8b 48 58 48 c7 c6 20 0c
RSP: 0018:ffff88018eb271d8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8801da979480 RCX: ffffea0007658e87
RDX: 0000000000000000 RSI: ffffffff8139ec96 RDI: 0000000000000007
RBP: ffff88018eb271f8 R08: ffff88018e3f03c0 R09: ffffed003914bb50
R10: ffffed003914bb50 R11: ffff8801c8a5da83 R12: ffff8801d963ab10
R13: ffff8801b37755a0 R14: ffff8801b37755a0 R15: ffff8801b3775590
FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 00000001c0bd1000 CR4: 00000000001426e0
Call Trace:
  anon_vma_chain_free mm/rmap.c:134 [inline]
  unlink_anon_vmas+0x5f0/0xa60 mm/rmap.c:419
  free_pgtables+0x271/0x380 mm/memory.c:393
  exit_mmap+0x2cd/0x590 mm/mmap.c:3146
  __mmput kernel/fork.c:1044 [inline]
  mmput+0x247/0x610 kernel/fork.c:1065
  exec_mmap fs/exec.c:1043 [inline]
  flush_old_exec+0xb91/0x21b0 fs/exec.c:1276
  load_elf_binary+0xa39/0x5620 fs/binfmt_elf.c:869
  search_binary_handler+0x17d/0x570 fs/exec.c:1653
  exec_binprm fs/exec.c:1695 [inline]
  __do_execve_file.isra.33+0x1661/0x25d0 fs/exec.c:1819
  do_execveat_common fs/exec.c:1866 [inline]
  do_execve fs/exec.c:1883 [inline]
  __do_sys_execve fs/exec.c:1964 [inline]
  __se_sys_execve fs/exec.c:1959 [inline]
  __x64_sys_execve+0x8f/0xc0 fs/exec.c:1959
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7ffa0b953207
Code: Bad RIP value.
RSP: 002b:00007ffefdbbcde8 EFLAGS: 00000206 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007ffa0b953207
RDX: 0000000000e42b70 RSI: 00007ffefdbbcee0 RDI: 00007ffefdbbdef0
RBP: 0000000000625500 R08: 000000000000405a R09: 000000000000405a
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000e42b70
R13: 0000000000000007 R14: 0000000000d40030 R15: 0000000000000005
Modules linked in:
CR2: 0000000000000080
kobject: 'loop5' (00000000598b220f): kobject_uevent_env
---[ end trace fc838222524811c3 ]---
RIP: 0010:slab_equal_or_root mm/slab.h:228 [inline]
RIP: 0010:cache_from_obj mm/slab.h:374 [inline]
RIP: 0010:kmem_cache_free+0x120/0x290 mm/slab.c:3752
kobject: 'loop5' (00000000598b220f): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
Code: ea ff ff 48 c1 e8 0c 48 c1 e0 06 48 01 d0 48 8b 50 08 48 8d 4a ff 83  
e2 01 48 0f 45 c1 48 8b 40 18 48 39 c3 0f 84 00 ff ff ff <48> 3b 98 80 00  
00 00 0f 84 11 01 00 00 48 8b 48 58 48 c7 c6 20 0c
RSP: 0018:ffff88018eb271d8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8801da979480 RCX: ffffea0007658e87
kobject: 'loop1' (00000000606593e3): kobject_uevent_env
kobject: 'loop2' (00000000a62421b8): kobject_uevent_env
kobject: 'loop1' (00000000606593e3): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000a62421b8): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
RDX: 0000000000000000 RSI: ffffffff8139ec96 RDI: 0000000000000007
RBP: ffff88018eb271f8 R08: ffff88018e3f03c0 R09: ffffed003914bb50
R10: ffffed003914bb50 R11: ffff8801c8a5da83 R12: ffff8801d963ab10
R13: ffff8801b37755a0 R14: ffff8801b37755a0 R15: ffff8801b3775590
kasan: CONFIG_KASAN_INLINE enabled
kobject: 'loop5' (00000000598b220f): kobject_uevent_env
FS:  00007ffa0c26f7a0(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
kasan: GPF could be caused by NULL-ptr deref or user memory access
kobject: 'loop5' (00000000598b220f): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop2' (00000000a62421b8): kobject_uevent_env
general protection fault: 0000 [#2] PREEMPT SMP KASAN
CPU: 1 PID: 16046 Comm: udevd Tainted: G      D           4.19.0+ #85
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__anon_vma_interval_tree_insert mm/interval_tree.c:72 [inline]
RIP: 0010:anon_vma_interval_tree_insert+0x179/0x370 mm/interval_tree.c:83
Code: 03 42 80 3c 3a 00 0f 85 7d 01 00 00 4d 8b 65 00 4d 85 e4 0f 84 a5 00  
00 00 e8 b3 fc cf ff 49 8d 7c 24 18 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00  
0f 85 75 01 00 00 4d 8b 6c 24 18 4c 89 f7 4c 89 ee
RSP: 0018:ffff8801c3396c90 EFLAGS: 00010206
RAX: 000000000836b159 RBX: ffff8801d8a8eee0 RCX: ffffffff81af3d90
RDX: 0000000000000000 RSI: ffffffff81af3d0d RDI: 0000000041b58acb
RBP: ffff8801c3396cd8 R08: ffff880183b76340 R09: 0000000000000000
R10: 00000000224b4293 R11: ffff880183b76340 R12: 0000000041b58ab3
R13: ffff8801d963dfc0 R14: 000000000000001f R15: dffffc0000000000
FS:  00007ffa0c26f7a0(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000930004 CR3: 000000018800a000 CR4: 00000000001426e0
Call Trace:
  anon_vma_chain_link mm/rmap.c:144 [inline]
  anon_vma_clone+0x2f5/0x710 mm/rmap.c:279
  anon_vma_fork+0xf4/0x820 mm/rmap.c:332
  dup_mmap kernel/fork.c:539 [inline]
  dup_mm kernel/fork.c:1317 [inline]
  copy_mm kernel/fork.c:1372 [inline]
  copy_process+0x47cc/0x8770 kernel/fork.c:1916
  _do_fork+0x1cb/0x11d0 kernel/fork.c:2213
  __do_sys_clone kernel/fork.c:2320 [inline]
  __se_sys_clone kernel/fork.c:2314 [inline]
  __x64_sys_clone+0xbf/0x150 kernel/fork.c:2314
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7ffa0b952f46
Code: f7 d8 64 89 04 25 d4 02 00 00 64 4c 8b 14 25 10 00 00 00 31 d2 49 81  
c2 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff  
ff 0f 87 31 01 00 00 85 c0 41 89 c4 0f 85 3b 01 00
RSP: 002b:00007ffefdbbcd80 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffefdbbcd80 RCX: 00007ffa0b952f46
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffefdbbcde0 R08: 0000000000003eae R09: 0000000000003eae
R10: 00007ffa0c26fa70 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffefdbbcda0 R14: 0000000000000005 R15: 0000000000000005
Modules linked in:
kobject: 'loop1' (00000000606593e3): kobject_uevent_env
kobject: 'loop2' (00000000a62421b8): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000606593e3): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
EXT4-fs (loop5): Can't read superblock on 2nd try
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop4' (000000001ebc1bae): kobject_uevent_env
kobject: 'loop4' (000000001ebc1bae): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
CR2: 00000000004ede98 CR3: 00000001c0bd1000 CR4: 00000000001426e0
FAT-fs (loop1): Directory bread(block 64) failed
kobject: 'loop5' (00000000598b220f): kobject_uevent_env
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
EXT4-fs (loop2): Invalid log block size: 2949122
kobject: 'loop5' (00000000598b220f): kobject_uevent_env
FAT-fs (loop1): Directory bread(block 65) failed
kobject: 'loop5' (00000000598b220f): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop5' (00000000598b220f): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
FAT-fs (loop1): Directory bread(block 66) failed
kobject: 'loop2' (00000000a62421b8): kobject_uevent_env


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