[v6.1] KASAN: slab-out-of-bounds Read in copy_page_from_iter_atomic

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0102425ac76b Linux 6.1.24
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=168b895bc80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f23561925d39903
dashboard link: https://syzkaller.appspot.com/bug?extid=ae02bc0f2673abd0edaa
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/11b4f76a294e/disk-0102425a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/45c8eec62c60/vmlinux-0102425a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0a7b8f48ec43/Image-0102425a.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae02bc...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in copy_page_from_iter_atomic+0x9a4/0x1104 lib/iov_iter.c:820
Read of size 4096 at addr ffff000128086000 by task kworker/u4:15/5965

CPU: 0 PID: 5965 Comm: kworker/u4:15 Not tainted 6.1.24-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: loop2 loop_workfn
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x174/0x4c0 mm/kasan/report.c:395
kasan_report+0xd4/0x130 mm/kasan/report.c:495
kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189
memcpy+0x48/0x90 mm/kasan/shadow.c:65
copy_page_from_iter_atomic+0x9a4/0x1104 lib/iov_iter.c:820
generic_perform_write+0x2fc/0x55c mm/filemap.c:3762
__generic_file_write_iter+0x168/0x388 mm/filemap.c:3882
generic_file_write_iter+0xb8/0x2b4 mm/filemap.c:3914
do_iter_write+0x534/0x964 fs/read_write.c:861
vfs_iter_write+0x88/0xac fs/read_write.c:902
lo_write_bvec drivers/block/loop.c:249 [inline]
lo_write_simple drivers/block/loop.c:271 [inline]
do_req_filebacked drivers/block/loop.c:495 [inline]
loop_handle_cmd drivers/block/loop.c:1882 [inline]
loop_process_work+0x15fc/0x256c drivers/block/loop.c:1917
loop_workfn+0x54/0x68 drivers/block/loop.c:1941
process_one_work+0x7ac/0x1404 kernel/workqueue.c:2289
worker_thread+0x8e4/0xfec kernel/workqueue.c:2436
kthread+0x24c/0x2d4 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

Allocated by task 6228:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:955 [inline]
__kmalloc+0xd8/0x1c4 mm/slab_common.c:968
kmalloc include/linux/slab.h:558 [inline]
hfsplus_read_wrapper+0x3ac/0xfcc fs/hfsplus/wrapper.c:178
hfsplus_fill_super+0x2f0/0x166c fs/hfsplus/super.c:413
mount_bdev+0x26c/0x368 fs/super.c:1423
hfsplus_mount+0x44/0x58 fs/hfsplus/super.c:641
legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
vfs_get_tree+0x90/0x274 fs/super.c:1553
do_new_mount+0x25c/0x8c8 fs/namespace.c:3040
path_mount+0x590/0xe58 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3568
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

The buggy address belongs to the object at ffff000128086000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff000128086000, ffff000128086200)

The buggy address belongs to the physical page:
page:00000000cafd76b0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x168084
head:00000000cafd76b0 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002600
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff000128086100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff000128086180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff000128086200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff000128086280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff000128086300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: ca48fc16c493 Linux 6.1.27
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13eefa8c280000
kernel config: https://syzkaller.appspot.com/x/.config?x=aea4bb7802570997

dashboard link: https://syzkaller.appspot.com/bug?extid=ae02bc0f2673abd0edaa
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157d5e10280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1574f822280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ec11c1903c52/disk-ca48fc16.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8ce41c1ad391/vmlinux-ca48fc16.xz
kernel image: https://storage.googleapis.com/syzbot-assets/affba5631cad/Image-ca48fc16.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f8690d5ba8da/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae02bc...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in copy_page_from_iter_atomic+0x9a4/0x1104 lib/iov_iter.c:820

Read of size 1024 at addr ffff0000d97c8c00 by task kworker/u4:2/39

CPU: 0 PID: 39 Comm: kworker/u4:2 Not tainted 6.1.27-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
Workqueue: loop0 loop_rootcg_workfn

Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x174/0x4c0 mm/kasan/report.c:395
kasan_report+0xd4/0x130 mm/kasan/report.c:495
kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189
memcpy+0x48/0x90 mm/kasan/shadow.c:65
copy_page_from_iter_atomic+0x9a4/0x1104 lib/iov_iter.c:820
generic_perform_write+0x2fc/0x55c mm/filemap.c:3762
__generic_file_write_iter+0x168/0x388 mm/filemap.c:3882
generic_file_write_iter+0xb8/0x2b4 mm/filemap.c:3914
do_iter_write+0x534/0x964 fs/read_write.c:861
vfs_iter_write+0x88/0xac fs/read_write.c:902
lo_write_bvec drivers/block/loop.c:249 [inline]
lo_write_simple drivers/block/loop.c:271 [inline]
do_req_filebacked drivers/block/loop.c:495 [inline]
loop_handle_cmd drivers/block/loop.c:1882 [inline]
loop_process_work+0x15fc/0x256c drivers/block/loop.c:1917

loop_rootcg_workfn+0x28/0x38 drivers/block/loop.c:1948

process_one_work+0x7ac/0x1404 kernel/workqueue.c:2289
worker_thread+0x8e4/0xfec kernel/workqueue.c:2436

kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

Allocated by task 4216:

The buggy address belongs to the object at ffff0000d97c8c00

which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of

512-byte region [ffff0000d97c8c00, ffff0000d97c8e00)

The buggy address belongs to the physical page:

page:000000006877335d refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1197c8
head:000000006877335d order:2 compound_mapcount:0 compound_pincount:0

flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002600

raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff0000d97c8d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff0000d97c8d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000d97c8e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff0000d97c8e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000d97c8f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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