KASAN: use-after-free Write in ucma_put_ctx

From: syzbot
Date: Fri Sep 07 2018 - 04:01:08 EST

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Hello,

syzbot found the following crash on:

HEAD commit: b36fdc6853a3 Merge tag 'gpio-v4.19-2' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16a18421400000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c9564cd177daf0c
dashboard link: https://syzkaller.appspot.com/bug?extid=cfe3c1e8ef634ba8964b
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=154f2056400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+cfe3c1e8ef634ba8964b@xxxxxxxxxxxxxxxxxxxxxxxxx

IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
hrtimer: interrupt took 27351 ns
==================================================================
BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
BUG: KASAN: use-after-free in ucma_put_ctx+0x1d/0x60 drivers/infiniband/core/ucma.c:158
Write of size 4 at addr ffff8801d9193858 by task syz-executor0/5348

CPU: 1 PID: 5348 Comm: syz-executor0 Not tainted 4.19.0-rc2+ #224
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
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278
atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
ucma_put_ctx+0x1d/0x60 drivers/infiniband/core/ucma.c:158
ucma_resolve_ip+0x24d/0x2a0 drivers/infiniband/core/ucma.c:713
ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1680
__vfs_write+0x117/0x9d0 fs/read_write.c:485
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457099
Code: fd b4 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f95c9f42c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f95c9f436d4 RCX: 0000000000457099
RDX: 0000000000000048 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d8100 R14: 00000000004c1c28 R15: 0000000000000001

Allocated by task 5348:
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
kmem_cache_alloc_trace+0x152/0x730 mm/slab.c:3620
kmalloc include/linux/slab.h:513 [inline]
kzalloc include/linux/slab.h:707 [inline]
ucma_alloc_ctx+0xd5/0x670 drivers/infiniband/core/ucma.c:205
ucma_create_id+0x276/0x9d0 drivers/infiniband/core/ucma.c:496
ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1680
__vfs_write+0x117/0x9d0 fs/read_write.c:485
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5344:
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+0xd9/0x210 mm/slab.c:3813
ucma_free_ctx+0x9e2/0xe20 drivers/infiniband/core/ucma.c:595
ucma_close+0x10d/0x300 drivers/infiniband/core/ucma.c:1764
__fput+0x38a/0xa40 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d9193800
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 88 bytes inside of
256-byte region [ffff8801d9193800, ffff8801d9193900)
The buggy address belongs to the page:
page:ffffea00076464c0 count:1 mapcount:0 mapping:ffff8801dac007c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0007658488 ffffea000766a688 ffff8801dac007c0
raw: 0000000000000000 ffff8801d9193080 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d9193700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801d9193780: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8801d9193800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8801d9193880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d9193900: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: AKASHI Takahiro: "[PATCH v14 11/16] arm64: kexec_file: allow for loading Image-format kernel"
Previous message: AKASHI Takahiro: "[PATCH v14 10/16] arm64: kexec_file: load initrd and device-tree"
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