[syzbot] [bcachefs?] KASAN: stack-out-of-bounds Read in __bch2_encrypt_bio

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 75fa778d74b7 Add linux-next specific files for 20240510
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17a13f70980000
kernel config: https://syzkaller.appspot.com/x/.config?x=ccdd3ebd6715749a
dashboard link: https://syzkaller.appspot.com/bug?extid=fff6b0fb00259873576a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1679303f180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a2743f180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad9391835bcf/disk-75fa778d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d827b3da9a26/vmlinux-75fa778d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f32f0182388/bzImage-75fa778d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/134862d610aa/mount_0.gz

The issue was bisected to:

commit 023f9ac9f70fbb1d94d27583fc06225355c73a67
Author: Kent Overstreet <kent.ov...@linux.dev>
Date: Wed Dec 20 02:58:20 2023 +0000

bcachefs: Delete dio read alignment check

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=130be15c980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=108be15c980000
console output: https://syzkaller.appspot.com/x/log.txt?x=170be15c980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fff6b0...@syzkaller.appspotmail.com
Fixes: 023f9ac9f70f ("bcachefs: Delete dio read alignment check")

==================================================================
BUG: KASAN: stack-out-of-bounds in sg_mark_end include/linux/scatterlist.h:258 [inline]
BUG: KASAN: stack-out-of-bounds in __bch2_encrypt_bio+0x84d/0xb10 fs/bcachefs/checksum.c:355
Read of size 8 at addr ffffc900001176a0 by task kworker/u8:1/12

CPU: 0 PID: 12 Comm: kworker/u8:1 Not tainted 6.9.0-rc7-next-20240510-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: events_unbound __bch2_read_endio
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
sg_mark_end include/linux/scatterlist.h:258 [inline]
__bch2_encrypt_bio+0x84d/0xb10 fs/bcachefs/checksum.c:355
bch2_encrypt_bio fs/bcachefs/checksum.h:97 [inline]
__bch2_read_endio+0x8ab/0x23c0 fs/bcachefs/io_read.c:601
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

The buggy address belongs to stack of task kworker/u8:1/12
and is located at offset 1120 in frame:
__bch2_encrypt_bio+0x0/0xb10 fs/bcachefs/checksum.c:72

This frame has 5 objects:
[32, 48) 'nonce.i115'
[64, 528) '__req_desc.i116'
[592, 608) 'nonce.i'
[624, 1088) '__req_desc.i'
[1152, 1664) 'sgl'

The buggy address belongs to the virtual mapping at
[ffffc90000110000, ffffc90000119000) created by:
copy_process+0x5d1/0x3dc0 kernel/fork.c:2220

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17297
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 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 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_ZERO), pid 2, tgid 2 (kthreadd), ts 2480284041, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
prep_new_page mm/page_alloc.c:1476 [inline]
get_page_from_freelist+0x2ce2/0x2d90 mm/page_alloc.c:3438
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4696
alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
vm_area_alloc_pages mm/vmalloc.c:3567 [inline]
__vmalloc_area_node mm/vmalloc.c:3643 [inline]
__vmalloc_node_range_noprof+0x9a4/0x1490 mm/vmalloc.c:3824
alloc_thread_stack_node kernel/fork.c:309 [inline]
dup_task_struct+0x444/0x8c0 kernel/fork.c:1115
copy_process+0x5d1/0x3dc0 kernel/fork.c:2220
kernel_clone+0x226/0x8f0 kernel/fork.c:2797
kernel_thread+0x1bc/0x240 kernel/fork.c:2859
create_kthread kernel/kthread.c:412 [inline]
kthreadd+0x60d/0x810 kernel/kthread.c:765
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
page_owner free stack trace missing

Memory state around the buggy address:
ffffc90000117580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc90000117600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90000117680: f2 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00
^
ffffc90000117700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc90000117780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


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