[v6.6] KASAN: use-after-free Read in z_erofs_transform_plain
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syzbot
Jun 24, 2025, 8:21:32 AM6/24/25
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1125fb0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a94f03...@syzkaller.appspotmail.com
syz.0.526: attempt to access beyond end of device
loop0: rw=524288, sector=16, nr_sectors = 8 limit=16
syz.0.526: attempt to access beyond end of device
loop0: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: use-after-free in memcpy_to_page include/linux/highmem.h:427 [inline]
BUG: KASAN: use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff88802e083400 by task syz.0.526/7906
CPU: 0 PID: 7906 Comm: syz.0.526 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x230 mm/kasan/report.c:475
kasan_report+0x117/0x150 mm/kasan/report.c:588
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
memcpy_to_page include/linux/highmem.h:427 [inline]
z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
z_erofs_decompress_pcluster fs/erofs/zdata.c:1290 [inline]
z_erofs_decompress_queue+0x16fb/0x2650 fs/erofs/zdata.c:1371
z_erofs_runqueue+0x18a3/0x19d0 fs/erofs/zdata.c:1759
z_erofs_readahead+0xa7c/0xd50 fs/erofs/zdata.c:1888
read_pages+0x177/0x840 mm/readahead.c:160
page_cache_ra_unbounded+0x692/0x770 mm/readahead.c:269
do_page_cache_ra mm/readahead.c:299 [inline]
force_page_cache_ra+0x2c1/0x320 mm/readahead.c:330
force_page_cache_readahead mm/internal.h:175 [inline]
generic_fadvise+0x44f/0x730 mm/fadvise.c:106
vfs_fadvise mm/fadvise.c:185 [inline]
ksys_fadvise64_64 mm/fadvise.c:199 [inline]
__do_sys_fadvise64 mm/fadvise.c:214 [inline]
__se_sys_fadvise64 mm/fadvise.c:212 [inline]
__x64_sys_fadvise64+0x140/0x180 mm/fadvise.c:212
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f72fc58e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f72fc3ff038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007f72fc7b6080 RCX: 00007f72fc58e929
RDX: 000000000000ff39 RSI: 000000000000aa1f RDI: 0000000000000004
RBP: 00007f72fc610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f72fc7b6080 R15: 00007ffea7444de8
</TASK>
The buggy address belongs to the physical page:
page:ffffea0000b820c0 refcount:2 mapcount:0 mapping:ffff8880760f87c8 index:0x1 pfn:0x2e083
memcg:ffff88807be34000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0000bc9748 ffffea0001e79708 ffff8880760f87c8
raw: 0000000000000001 ffff88807e496000 00000002ffffffff ffff88807be34000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x192840(GFP_NOWAIT|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 7899, tgid 7898 (syz.0.526), ts 377671693309, free_ts 376794751944
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
z_erofs_bind_cache fs/erofs/zdata.c:599 [inline]
z_erofs_pcluster_begin fs/erofs/zdata.c:883 [inline]
z_erofs_do_read_page+0x20c0/0x3680 fs/erofs/zdata.c:1018
z_erofs_read_folio+0x213/0x540 fs/erofs/zdata.c:1839
filemap_read_folio+0x167/0x760 mm/filemap.c:2420
do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3789
erofs_bread+0x16f/0x630 fs/erofs/data.c:48
erofs_find_target_block fs/erofs/namei.c:103 [inline]
erofs_namei+0x28c/0xf00 fs/erofs/namei.c:177
erofs_lookup+0x135/0x310 fs/erofs/namei.c:206
__lookup_slow+0x281/0x3b0 fs/namei.c:1694
lookup_slow+0x53/0x70 fs/namei.c:1711
walk_component fs/namei.c:2002 [inline]
link_path_walk+0x970/0xe00 fs/namei.c:2329
path_openat+0x283/0x3190 fs/namei.c:3785
do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
release_pages+0x1fa0/0x2220 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
exit_mmap+0x3f0/0xb50 mm/mmap.c:3305
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1da/0x2c0 kernel/exit.c:569
do_exit+0x886/0x23c0 kernel/exit.c:861
do_group_exit+0x21b/0x2d0 kernel/exit.c:1023
__do_sys_exit_group kernel/exit.c:1034 [inline]
__se_sys_exit_group kernel/exit.c:1032 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Memory state around the buggy address:
ffff88802e083f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88802e083f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802e084000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88802e084080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88802e084100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
---
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.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1125fb0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a94f03...@syzkaller.appspotmail.com
syz.0.526: attempt to access beyond end of device
loop0: rw=524288, sector=16, nr_sectors = 8 limit=16
syz.0.526: attempt to access beyond end of device
loop0: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: use-after-free in memcpy_to_page include/linux/highmem.h:427 [inline]
BUG: KASAN: use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff88802e083400 by task syz.0.526/7906
CPU: 0 PID: 7906 Comm: syz.0.526 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x230 mm/kasan/report.c:475
kasan_report+0x117/0x150 mm/kasan/report.c:588
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
memcpy_to_page include/linux/highmem.h:427 [inline]
z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
z_erofs_decompress_pcluster fs/erofs/zdata.c:1290 [inline]
z_erofs_decompress_queue+0x16fb/0x2650 fs/erofs/zdata.c:1371
z_erofs_runqueue+0x18a3/0x19d0 fs/erofs/zdata.c:1759
z_erofs_readahead+0xa7c/0xd50 fs/erofs/zdata.c:1888
read_pages+0x177/0x840 mm/readahead.c:160
page_cache_ra_unbounded+0x692/0x770 mm/readahead.c:269
do_page_cache_ra mm/readahead.c:299 [inline]
force_page_cache_ra+0x2c1/0x320 mm/readahead.c:330
force_page_cache_readahead mm/internal.h:175 [inline]
generic_fadvise+0x44f/0x730 mm/fadvise.c:106
vfs_fadvise mm/fadvise.c:185 [inline]
ksys_fadvise64_64 mm/fadvise.c:199 [inline]
__do_sys_fadvise64 mm/fadvise.c:214 [inline]
__se_sys_fadvise64 mm/fadvise.c:212 [inline]
__x64_sys_fadvise64+0x140/0x180 mm/fadvise.c:212
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f72fc58e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f72fc3ff038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007f72fc7b6080 RCX: 00007f72fc58e929
RDX: 000000000000ff39 RSI: 000000000000aa1f RDI: 0000000000000004
RBP: 00007f72fc610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f72fc7b6080 R15: 00007ffea7444de8
</TASK>
The buggy address belongs to the physical page:
page:ffffea0000b820c0 refcount:2 mapcount:0 mapping:ffff8880760f87c8 index:0x1 pfn:0x2e083
memcg:ffff88807be34000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0000bc9748 ffffea0001e79708 ffff8880760f87c8
raw: 0000000000000001 ffff88807e496000 00000002ffffffff ffff88807be34000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x192840(GFP_NOWAIT|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 7899, tgid 7898 (syz.0.526), ts 377671693309, free_ts 376794751944
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
z_erofs_bind_cache fs/erofs/zdata.c:599 [inline]
z_erofs_pcluster_begin fs/erofs/zdata.c:883 [inline]
z_erofs_do_read_page+0x20c0/0x3680 fs/erofs/zdata.c:1018
z_erofs_read_folio+0x213/0x540 fs/erofs/zdata.c:1839
filemap_read_folio+0x167/0x760 mm/filemap.c:2420
do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3789
erofs_bread+0x16f/0x630 fs/erofs/data.c:48
erofs_find_target_block fs/erofs/namei.c:103 [inline]
erofs_namei+0x28c/0xf00 fs/erofs/namei.c:177
erofs_lookup+0x135/0x310 fs/erofs/namei.c:206
__lookup_slow+0x281/0x3b0 fs/namei.c:1694
lookup_slow+0x53/0x70 fs/namei.c:1711
walk_component fs/namei.c:2002 [inline]
link_path_walk+0x970/0xe00 fs/namei.c:2329
path_openat+0x283/0x3190 fs/namei.c:3785
do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
release_pages+0x1fa0/0x2220 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
exit_mmap+0x3f0/0xb50 mm/mmap.c:3305
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1da/0x2c0 kernel/exit.c:569
do_exit+0x886/0x23c0 kernel/exit.c:861
do_group_exit+0x21b/0x2d0 kernel/exit.c:1023
__do_sys_exit_group kernel/exit.c:1034 [inline]
__se_sys_exit_group kernel/exit.c:1032 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Memory state around the buggy address:
ffff88802e083f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88802e083f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802e084000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88802e084080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88802e084100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
---
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.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Jun 25, 2025, 11:13:37 PM6/25/25
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13fbbdd4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12853f0c580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/902b6b477700/mount_1.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10a45b70580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a94f03...@syzkaller.appspotmail.com
loop0: rw=524288, sector=720, nr_sectors = 16 limit=16
syz-executor150: attempt to access beyond end of device
loop0: rw=524288, sector=525144, nr_sectors = 16 limit=16
syz-executor150: attempt to access beyond end of device
BUG: KASAN: slab-use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff88807b8d7400 by task syz-executor150/5769
CPU: 0 PID: 5769 Comm: syz-executor150 Not tainted 6.6.94-syzkaller #0
RIP: 0033:0x7f16442791f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 1f 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee6c44908 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f16442791f9
R10: 0000000000000003 R11: 0000000000000246 R12: 00007f16442c658f
R13: 0000000000000003 R14: 0000000000050012 R15: 00007f16442fc740
memcg:ffff88814125a000
raw: 0000000000000001 ffff888073db4000 00000002ffffffff ffff88814125a000
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2122 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2662
put_cpu_partial+0x17c/0x250 mm/slub.c:2738
__slab_free+0x31d/0x410 mm/slub.c:3686
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3524
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa4/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x20f/0x4b0 security/tomoyo/file.c:822
security_inode_getattr+0xd3/0x120 security/security.c:2153
vfs_getattr fs/stat.c:173 [inline]
vfs_fstat fs/stat.c:198 [inline]
__do_sys_newfstat fs/stat.c:473 [inline]
__se_sys_newfstat fs/stat.c:470 [inline]
__x64_sys_newfstat+0x101/0x1f0 fs/stat.c:470
ffff88807b8d7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807b8d8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807b8d8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b8d8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c53182580000
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12853f0c580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10a45b70580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a94f03...@syzkaller.appspotmail.com
syz-executor150: attempt to access beyond end of device
loop0: rw=524288, sector=525144, nr_sectors = 16 limit=16
syz-executor150: attempt to access beyond end of device
loop0: rw=524288, sector=16, nr_sectors = 8 limit=16
syz-executor150: attempt to access beyond end of device
loop0: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: slab-use-after-free in memcpy_to_page include/linux/highmem.h:427 [inline]
==================================================================
BUG: KASAN: slab-use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff88807b8d7400 by task syz-executor150/5769
CPU: 0 PID: 5769 Comm: syz-executor150 Not tainted 6.6.94-syzkaller #0
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 1f 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee6c44908 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f16442791f9
RDX: 000000000000ff39 RSI: 000000000000aa1f RDI: 0000000000000004
RBP: 00007f16442c660e R08: 00007f16442c663e R09: 00007f16442c663e
R10: 0000000000000003 R11: 0000000000000246 R12: 00007f16442c658f
R13: 0000000000000003 R14: 0000000000050012 R15: 00007f16442fc740
</TASK>
The buggy address belongs to the physical page:
page:ffffea0001ee35c0 refcount:2 mapcount:0 mapping:ffff888073db87c8 index:0x1 pfn:0x7b8d7
The buggy address belongs to the physical page:
memcg:ffff88814125a000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0001ee3588 ffffea0000954208 ffff888073db87c8
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 0000000000000001 ffff888073db4000 00000002ffffffff ffff88814125a000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x92840(GFP_NOWAIT|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC), pid 5769, tgid 5769 (syz-executor150), ts 84628441673, free_ts 64645641726
page_owner tracks the page as allocated
discard_slab mm/slub.c:2122 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2662
put_cpu_partial+0x17c/0x250 mm/slub.c:2738
__slab_free+0x31d/0x410 mm/slub.c:3686
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3524
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa4/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x20f/0x4b0 security/tomoyo/file.c:822
security_inode_getattr+0xd3/0x120 security/security.c:2153
vfs_getattr fs/stat.c:173 [inline]
vfs_fstat fs/stat.c:198 [inline]
__do_sys_newfstat fs/stat.c:473 [inline]
__se_sys_newfstat fs/stat.c:470 [inline]
__x64_sys_newfstat+0x101/0x1f0 fs/stat.c:470
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
Memory state around the buggy address:
ffff88807b8d7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88807b8d7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807b8d8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807b8d8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b8d8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
syzbot
Jul 11, 2025, 7:32:05 AM7/11/25
to syzkaller...@googlegroups.com
syzbot suspects this issue could be fixed by backporting the following commit:
commit 1ca01520148af399899ed66af5c78330bb9ecaf2
git tree: upstream
Author: Gao Xiang <hsia...@linux.alibaba.com>
Date: Wed Dec 6 09:10:56 2023 +0000
erofs: refine z_erofs_transform_plain() for sub-page block support
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13b58d82580000
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
commit 1ca01520148af399899ed66af5c78330bb9ecaf2
git tree: upstream
Author: Gao Xiang <hsia...@linux.alibaba.com>
Date: Wed Dec 6 09:10:56 2023 +0000
erofs: refine z_erofs_transform_plain() for sub-page block support
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13b58d82580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
dashboard link: https://syzkaller.appspot.com/bug?extid=a94f033f5bdbb0bd6999
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c53182580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12853f0c580000
Please keep in mind that other backports might be required as well.
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12853f0c580000
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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