KASAN: use-after-free Read in inet_create

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b98aebd2 Linux 4.14.150
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1128dd9b600000
kernel config: https://syzkaller.appspot.com/x/.config?x=c52c93b368dac5a7
dashboard link: https://syzkaller.appspot.com/bug?extid=c4baef56155e3a738f28
compiler: gcc (GCC) 9.0.0 20181231 (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+c4baef...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in inet_create net/ipv4/af_inet.c:337 [inline]
BUG: KASAN: use-after-free in inet_create+0xc31/0xca0 net/ipv4/af_inet.c:244
Read of size 4 at addr ffff88805dc0c744 by task syz-executor.3/6905

CPU: 1 PID: 6905 Comm: syz-executor.3 Not tainted 4.14.150 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x197 lib/dump_stack.c:53
print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
inet_create net/ipv4/af_inet.c:337 [inline]
inet_create+0xc31/0xca0 net/ipv4/af_inet.c:244
__sock_create+0x2f6/0x620 net/socket.c:1275
sock_create net/socket.c:1315 [inline]
SYSC_socket net/socket.c:1345 [inline]
SyS_socket+0xd3/0x170 net/socket.c:1325
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c5a7
RSP: 002b:00007fff0e4ff268 EFLAGS: 00000246
ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045c5a7
RDX: 0000000000000006 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 00000000000003ca R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff0e4ff980 R14: 000000000008629b R15: 00007fff0e4ff990

Allocated by task 17045:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
kmem_cache_alloc+0x12e/0x780 mm/slab.c:3552
getname_flags fs/namei.c:138 [inline]
getname_flags+0xcb/0x580 fs/namei.c:128
user_path_at_empty+0x2f/0x50 fs/namei.c:2630
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0xcd/0x160 fs/stat.c:185
vfs_stat include/linux/fs.h:3060 [inline]
SYSC_newstat+0x95/0x100 fs/stat.c:337
SyS_newstat+0x1e/0x30 fs/stat.c:333
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 17045:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
putname+0xdb/0x120 fs/namei.c:259
filename_lookup+0x23a/0x380 fs/namei.c:2385
user_path_at_empty+0x43/0x50 fs/namei.c:2630
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0xcd/0x160 fs/stat.c:185
vfs_stat include/linux/fs.h:3060 [inline]
SYSC_newstat+0x95/0x100 fs/stat.c:337
SyS_newstat+0x1e/0x30 fs/stat.c:333
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88805dc0c580
which belongs to the cache names_cache of size 4096
The buggy address is located 452 bytes inside of
4096-byte region [ffff88805dc0c580, ffff88805dc0d580)
The buggy address belongs to the page:
page:ffffea0001770300 count:1 mapcount:0 mapping:ffff88805dc0c580 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffff88805dc0c580 0000000000000000 0000000100000001
raw: ffffea00016db2a0 ffffea00017703a0 ffff8880aa9e0cc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88805dc0c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88805dc0c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88805dc0c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88805dc0c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88805dc0c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.