[syzbot] KASAN: use-after-free Read in tty_release

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syzbot

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Mar 22, 2022, 1:48:29 PM3/22/22
to asml.s...@gmail.com, ax...@kernel.dk, gre...@linuxfoundation.org, io-u...@vger.kernel.org, jiri...@kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 8565d64430f8 Merge tag 'bounds-fixes-v5.18-rc1' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=118a7913700000
kernel config: https://syzkaller.appspot.com/x/.config?x=89040bbe61f60a52
dashboard link: https://syzkaller.appspot.com/bug?extid=09ad4050dd3a120bfccd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=124eed75700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11fbbb35700000

The issue was bisected to:

commit 91eac1c69c202d9dad8bf717ae5b92db70bfe5cf
Author: Jens Axboe <ax...@kernel.dk>
Date: Wed Mar 16 22:59:10 2022 +0000

io_uring: cache poll/double-poll state with a request flag

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12e4ae0b700000
final oops: https://syzkaller.appspot.com/x/report.txt?x=11e4ae0b700000
console output: https://syzkaller.appspot.com/x/log.txt?x=16e4ae0b700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09ad40...@syzkaller.appspotmail.com
Fixes: 91eac1c69c20 ("io_uring: cache poll/double-poll state with a request flag")

==================================================================
BUG: KASAN: use-after-free in __wake_up_common+0x637/0x650 kernel/sched/wait.c:101
Read of size 8 at addr ffff888011e8a130 by task syz-executor413/3618

CPU: 0 PID: 3618 Comm: syz-executor413 Tainted: G W 5.17.0-syzkaller-01402-g8565d64430f8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
__wake_up_common+0x637/0x650 kernel/sched/wait.c:101
__wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:138
tty_release+0x657/0x1200 drivers/tty/tty_io.c:1781
__fput+0x286/0x9f0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0xaff/0x29d0 kernel/exit.c:806
do_group_exit+0xd2/0x2f0 kernel/exit.c:936
__do_sys_exit_group kernel/exit.c:947 [inline]
__se_sys_exit_group kernel/exit.c:945 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:945
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f439a1fac69
Code: Unable to access opcode bytes at RIP 0x7f439a1fac3f.
RSP: 002b:00007ffd9df32928 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f439a26f330 RCX: 00007f439a1fac69
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000030000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f439a26f330
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
</TASK>

Allocated by task 3610:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:524
kasan_kmalloc include/linux/kasan.h:249 [inline]
kmem_cache_alloc_trace+0x1ea/0x4a0 mm/slab.c:3567
kmalloc include/linux/slab.h:581 [inline]
io_arm_poll_handler+0x39d/0x940 fs/io_uring.c:6248
io_queue_sqe_arm_apoll+0x6d/0x430 fs/io_uring.c:7499
__io_queue_sqe fs/io_uring.c:7541 [inline]
io_queue_sqe fs/io_uring.c:7568 [inline]
io_submit_sqe fs/io_uring.c:7776 [inline]
io_submit_sqes+0x7dda/0x9310 fs/io_uring.c:7882
__do_sys_io_uring_enter+0x9f1/0x1520 fs/io_uring.c:10924
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 3610:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0xff/0x140 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:215 [inline]
__cache_free mm/slab.c:3437 [inline]
kfree+0xf8/0x2b0 mm/slab.c:3794
io_clean_op+0x20a/0xd90 fs/io_uring.c:7137
io_dismantle_req fs/io_uring.c:2270 [inline]
__io_req_complete_post+0x88c/0xc90 fs/io_uring.c:2108
io_req_complete_post+0x56/0x1d0 fs/io_uring.c:2121
io_apoll_task_func+0x1df/0x230 fs/io_uring.c:6003
handle_tw_list fs/io_uring.c:2480 [inline]
tctx_task_work+0x1a2/0x1380 fs/io_uring.c:2514
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0xaff/0x29d0 kernel/exit.c:806
do_group_exit+0xd2/0x2f0 kernel/exit.c:936
__do_sys_exit_group kernel/exit.c:947 [inline]
__se_sys_exit_group kernel/exit.c:945 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:945
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888011e8a100
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 48 bytes inside of
96-byte region [ffff888011e8a100, ffff888011e8a160)
The buggy address belongs to the page:
page:ffffea000047a280 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888011e8a480 pfn:0x11e8a
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea000079fc08 ffffea0001f1d088 ffff888010c40300
raw: ffff888011e8a480 ffff888011e8a000 000000010000001e 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 1, ts 3360715486, free_ts 0
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
__alloc_pages_node include/linux/gfp.h:572 [inline]
kmem_getpages mm/slab.c:1378 [inline]
cache_grow_begin+0x75/0x390 mm/slab.c:2584
cache_alloc_refill+0x27f/0x380 mm/slab.c:2957
____cache_alloc mm/slab.c:3040 [inline]
____cache_alloc mm/slab.c:3023 [inline]
__do_cache_alloc mm/slab.c:3267 [inline]
slab_alloc mm/slab.c:3308 [inline]
kmem_cache_alloc_trace+0x380/0x4a0 mm/slab.c:3565
kmalloc include/linux/slab.h:581 [inline]
kzalloc include/linux/slab.h:714 [inline]
hugetlbfs_init_fs_context+0x41/0x420 fs/hugetlbfs/inode.c:1402
alloc_fs_context+0x582/0xa00 fs/fs_context.c:290
mount_one_hugetlbfs+0x1d/0x14d fs/hugetlbfs/inode.c:1507
init_hugetlbfs_fs+0xd5/0x311 fs/hugetlbfs/inode.c:1546
do_one_initcall+0x103/0x650 init/main.c:1300
do_initcall_level init/main.c:1373 [inline]
do_initcalls init/main.c:1389 [inline]
do_basic_setup init/main.c:1408 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1613
kernel_init+0x1a/0x1d0 init/main.c:1502
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page_owner free stack trace missing

Memory state around the buggy address:
ffff888011e8a000: 00 00 00 00 00 00 00 00 00 05 fc fc fc fc fc fc
ffff888011e8a080: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888011e8a100: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff888011e8a180: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
ffff888011e8a200: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Jens Axboe

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Mar 22, 2022, 3:17:03 PM3/22/22
to syzbot, asml.s...@gmail.com, gre...@linuxfoundation.org, io-u...@vger.kernel.org, jiri...@kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
#syz test: git://git.kernel.dk/linux-block for-5.18/io_uring

--
Jens Axboe

syzbot

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Mar 22, 2022, 5:03:07 PM3/22/22
to asml.s...@gmail.com, ax...@kernel.dk, gre...@linuxfoundation.org, io-u...@vger.kernel.org, jiri...@kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+09ad40...@syzkaller.appspotmail.com

Tested on:

commit: 7d58de1a io_uring: don't recycle provided buffer if pu..
git tree: git://git.kernel.dk/linux-block for-5.18/io_uring
kernel config: https://syzkaller.appspot.com/x/.config?x=e8bdba3010ab9145
dashboard link: https://syzkaller.appspot.com/bug?extid=09ad4050dd3a120bfccd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.
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