KASAN: slab-out-of-bounds Write in tls_push_record

From: syzbot
Date: Sun Jun 10 2018 - 02:15:23 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 410feb75de24 Merge tag 'arm64-upstream' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1308a0cf800000
kernel config: https://syzkaller.appspot.com/x/.config?x=7c0dfd1fff57e223
dashboard link: https://syzkaller.appspot.com/bug?extid=5c74af81c547738e1684
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+5c74af81c547738e1684@xxxxxxxxxxxxxxxxxxxxxxxxx

RDX: 00000000fffffdef RSI: 00000000200005c0 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000020000000 R09: 000000000000001c
R10: 0000000000000040 R11: 0000000000000246 R12: 0000000000000015
R13: 00000000004c0d3b R14: 00000000004d07a8 R15: 0000000000000002
==================================================================
BUG: KASAN: slab-out-of-bounds in tls_fill_prepend include/net/tls.h:339 [inline]
BUG: KASAN: slab-out-of-bounds in tls_push_record+0x1023/0x13e0 net/tls/tls_sw.c:240
Write of size 1 at addr ffff8801bae68000 by task syz-executor1/24187

CPU: 1 PID: 24187 Comm: syz-executor1 Not tainted 4.17.0+ #91
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+0x1b9/0x294 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
__asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435
tls_fill_prepend include/net/tls.h:339 [inline]
tls_push_record+0x1023/0x13e0 net/tls/tls_sw.c:240
tls_sw_push_pending_record+0x22/0x30 net/tls/tls_sw.c:276
tls_push_pending_closed_record+0x10c/0x150 net/tls/tls_main.c:211
tls_complete_pending_work include/net/tls.h:277 [inline]
tls_sk_proto_close+0x8f2/0xad0 net/tls/tls_main.c:263
inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
sock_release+0x96/0x1b0 net/socket.c:598
sock_close+0x16/0x20 net/socket.c:1174
__fput+0x353/0x890 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x1e4/0x290 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1aee/0x2730 kernel/exit.c:865
do_group_exit+0x16f/0x430 kernel/exit.c:968
get_signal+0x886/0x1960 kernel/signal.c:2478
do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4559f9
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb96babace8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000072bec8 RCX: 00000000004559f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bec8
RBP: 000000000072bec8 R08: 0000000000000033 R09: 000000000072bea0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd163d2bff R14: 00007fb96babb9c0 R15: 0000000000000000

Allocated by task 24192:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
__do_kmalloc mm/slab.c:3718 [inline]
__kmalloc+0x14e/0x760 mm/slab.c:3727
kmalloc include/linux/slab.h:518 [inline]
rw_copy_check_uvector+0x31e/0x3a0 fs/read_write.c:781
import_iovec+0xc3/0x420 lib/iov_iter.c:1459
vfs_readv+0xe2/0x1a0 fs/read_write.c:984
do_preadv+0x1ba/0x270 fs/read_write.c:1070
__do_sys_preadv fs/read_write.c:1120 [inline]
__se_sys_preadv fs/read_write.c:1115 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 24192:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xd9/0x260 mm/slab.c:3813
import_iovec+0x32e/0x420 lib/iov_iter.c:1463
vfs_readv+0xe2/0x1a0 fs/read_write.c:984
do_preadv+0x1ba/0x270 fs/read_write.c:1070
__do_sys_preadv fs/read_write.c:1120 [inline]
__se_sys_preadv fs/read_write.c:1115 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801bae69f80
which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 8064 bytes to the left of
16384-byte region [ffff8801bae69f80, ffff8801bae6df80)
The buggy address belongs to the page:
page:ffffea0006eb9a00 count:1 mapcount:0 mapping:ffff8801da802200 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0005e2a408 ffff8801da801c48 ffff8801da802200
raw: 0000000000000000 ffff8801bae69f80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801bae67f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801bae67f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffff8801bae68000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

^
ffff8801bae68080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801bae68100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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Next message: Thomas Gleixner: "[GIT pull] x86 updates for 4.18"
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