[syzbot] KASAN: stack-out-of-bounds Read in __blk_flush_plug

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0d1409e4ff08 Merge tag 'drm-fixes-2022-12-09' of git://ano..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=170a308f880000
kernel config: https://syzkaller.appspot.com/x/.config?x=d58e7fe7f9cf5e24
dashboard link: https://syzkaller.appspot.com/bug?extid=27ad9fcb89d23f44ca81
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9ab0143f95cb/disk-0d1409e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e574d5eaa32f/vmlinux-0d1409e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/31109436b00b/bzImage-0d1409e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+27ad9f...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: stack-out-of-bounds in __blk_flush_plug+0x4ca/0x570 block/blk-core.c:1136
Read of size 8 at addr ffffc900031bf37f by task syz-executor.3/10381

CPU: 0 PID: 10381 Comm: syz-executor.3 Not tainted 6.1.0-rc8-syzkaller-00148-g0d1409e4ff08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
print_address_description+0x74/0x340 mm/kasan/report.c:284
print_report+0x107/0x1f0 mm/kasan/report.c:395
kasan_report+0xcd/0x100 mm/kasan/report.c:495
__blk_flush_plug+0x4ca/0x570 block/blk-core.c:1136
blk_finish_plug+0x5a/0x80 block/blk-core.c:1161
read_pages+0x7a8/0x9c0 mm/readahead.c:184
page_cache_ra_unbounded+0x703/0x820 mm/readahead.c:270
page_cache_sync_readahead include/linux/pagemap.h:1213 [inline]
filemap_get_pages+0x465/0x10d0 mm/filemap.c:2581
filemap_read+0x3cf/0xea0 mm/filemap.c:2675
call_read_iter include/linux/fs.h:2193 [inline]
generic_file_splice_read+0x1ff/0x5d0 fs/splice.c:309
do_splice_to fs/splice.c:793 [inline]
splice_direct_to_actor+0x41b/0xc00 fs/splice.c:865
do_splice_direct+0x279/0x3d0 fs/splice.c:974
do_sendfile+0x5fb/0xf80 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64+0x14f/0x1b0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0ef8e8c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0ef9c36168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f0ef8fabf80 RCX: 00007f0ef8e8c0d9
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000006
RBP: 00007f0ef8ee7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000f03b0000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff02d3b9cf R14: 00007f0ef9c36300 R15: 0000000000022000
</TASK>

The buggy address belongs to stack of task syz-executor.3/10381
and is located at offset 31 in frame:
read_pages+0x0/0x9c0 include/linux/page-flags.h:319

This frame has 1 object:
[32, 72) 'plug'

The buggy address belongs to the virtual mapping at
[ffffc900031b8000, ffffc900031c1000) created by:
dup_task_struct+0x8b/0x490 kernel/fork.c:974

The buggy address belongs to the physical page:
page:ffffea00008b5a40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x22d69
memcg:ffff888027c8ad02
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888027c8ad02
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 10379, tgid 10379 (syz-executor.3), ts 335022583921, free_ts 334826793550
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4291
__alloc_pages+0x259/0x560 mm/page_alloc.c:5558
vm_area_alloc_pages mm/vmalloc.c:2975 [inline]
__vmalloc_area_node mm/vmalloc.c:3043 [inline]
__vmalloc_node_range+0x9b2/0x1400 mm/vmalloc.c:3213
alloc_thread_stack_node+0x307/0x500 kernel/fork.c:311
dup_task_struct+0x8b/0x490 kernel/fork.c:974
copy_process+0x637/0x4000 kernel/fork.c:2084
kernel_clone+0x21b/0x620 kernel/fork.c:2671
__do_sys_clone kernel/fork.c:2812 [inline]
__se_sys_clone kernel/fork.c:2796 [inline]
__x64_sys_clone+0x228/0x290 kernel/fork.c:2796
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1459 [inline]
free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1509
free_unref_page_prepare mm/page_alloc.c:3387 [inline]
free_unref_page_list+0xb4/0x7b0 mm/page_alloc.c:3529
release_pages+0x232a/0x25c0 mm/swap.c:1055
tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
tlb_flush_mmu+0x850/0xa70 mm/mmu_gather.c:261
tlb_finish_mmu+0xcb/0x200 mm/mmu_gather.c:361
exit_mmap+0x275/0x630 mm/mmap.c:3102
__mmput+0x114/0x3b0 kernel/fork.c:1185
exit_mm+0x1f5/0x2d0 kernel/exit.c:516
do_exit+0x5e7/0x2070 kernel/exit.c:807
do_group_exit+0x1fd/0x2b0 kernel/exit.c:950
__do_sys_exit_group kernel/exit.c:961 [inline]
__se_sys_exit_group kernel/exit.c:959 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:959
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffffc900031bf200: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 f3 f3
ffffc900031bf280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900031bf300: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
^
ffffc900031bf380: 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3 00 00 00 00
ffffc900031bf400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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