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KASAN: slab-out-of-bounds Read in do_split

Status: premoderation: reported syz repro on 2025/02/13 04:57
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+030d9cb01ee98a1940ca@syzkaller.appspotmail.com
First crash: 148d, last: 4d07h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/02/13 lts (merge base) c16c81c81336 C [report] KASAN: use-after-free Read in do_split
2025/03/16 upstream (ToT) cb82ca153949 C [report] KASAN: slab-use-after-free Read in do_split
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 BUG: unable to handle kernel paging request in do_split 19 C error 25 9d11h 336d 0/2 upstream: reported C repro on 2024/08/09 00:52
linux-6.1 KASAN: use-after-free Read in do_split 19 1 245d 245d 0/3 auto-obsoleted due to no activity on 2025/02/15 19:28
upstream BUG: unable to handle kernel paging request in do_split ext4 8 C inconclusive 17 364d 376d 27/29 fixed on 2024/08/14 03:44
▶ ▼ Last patch testing requests (8)
Created Duration User Patch Repo Result
2025/07/06 22:27 45m retest repro android13-5.15-lts report log
2025/07/06 22:27 17m retest repro android13-5.15-lts report log
2025/07/06 22:27 17m retest repro android13-5.15-lts report log
2025/07/06 22:27 17m retest repro android13-5.15-lts report log
2025/07/06 22:27 9m retest repro android13-5.15-lts report log
2025/06/22 16:56 11m retest repro android13-5.15-lts report log
2025/06/08 03:45 30m retest repro android13-5.15-lts report log
2025/06/08 03:45 18m retest repro android13-5.15-lts report log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in dx_insert_block fs/ext4/namei.c:1387 [inline]
BUG: KASAN: slab-out-of-bounds in do_split+0x1a73/0x1f70 fs/ext4/namei.c:2080
Read of size 157024 at addr ffff88812816e028 by task syz.0.428/1582

CPU: 0 PID: 1582 Comm: syz.0.428 Not tainted 5.15.180-syzkaller-00024-g88c4075c39ed #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block fs/ext4/namei.c:1387 [inline]
 do_split+0x1a73/0x1f70 fs/ext4/namei.c:2080
 make_indexed_dir+0xe01/0x14a0 fs/ext4/namei.c:2392
 ext4_add_entry+0xc24/0xf40 fs/ext4/namei.c:2504
 __ext4_link+0x4d7/0x770 fs/ext4/namei.c:3536
 ext4_link+0x1de/0x270 fs/ext4/namei.c:3577
 vfs_link+0x636/0x7f0 fs/namei.c:4557
 do_linkat+0x1e7/0x730 fs/namei.c:4628
 __do_sys_link fs/namei.c:4662 [inline]
 __se_sys_link fs/namei.c:4660 [inline]
 __x64_sys_link+0x86/0x90 fs/namei.c:4660
 x64_sys_call+0x34d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:87
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f6ea6224969
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:00007f6ea5c95038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f6ea644bfa0 RCX: 00007f6ea6224969
RDX: 0000000000000000 RSI: 0000200000000bc0 RDI: 0000200000001240
RBP: 00007f6ea62a6ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6ea644bfa0 R15: 00007ffca01c18c8
 </TASK>

The buggy address belongs to the page:
page:ffffea0004a05b80 refcount:3 mapcount:1 mapping:ffff8881092d7a18 index:0x1 pfn:0x12816e
memcg:ffff88810024c000
aops:def_blk_aops ino:700000
flags: 0x400000000032201e(referenced|uptodate|dirty|lru|private|mappedtodisk|unevictable|mlocked|zone=1)
raw: 400000000032201e ffff888100240040 ffffea0004af9388 ffff8881092d7a18
raw: 0000000000000001 ffff888120ff9738 0000000300000000 ffff88810024c000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 1457, ts 176998997621, free_ts 169730171812
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5781
 __alloc_pages_node include/linux/gfp.h:591 [inline]
 alloc_pages_node include/linux/gfp.h:605 [inline]
 alloc_pages include/linux/gfp.h:618 [inline]
 __page_cache_alloc include/linux/pagemap.h:305 [inline]
 page_cache_ra_unbounded+0x2b2/0x980 mm/readahead.c:227
 do_page_cache_ra mm/readahead.c:280 [inline]
 force_page_cache_ra+0x3fd/0x460 mm/readahead.c:312
 page_cache_sync_ra+0x2ae/0x420 mm/readahead.c:590
 page_cache_sync_readahead include/linux/pagemap.h:831 [inline]
 filemap_get_pages mm/filemap.c:2560 [inline]
 filemap_read+0x63a/0x1f70 mm/filemap.c:2645
 generic_file_read_iter+0xac/0x400 mm/filemap.c:2805
 blkdev_read_iter+0x12f/0x160 block/fops.c:560
 call_read_iter include/linux/fs.h:2198 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x68b/0xbe0 fs/read_write.c:485
 ksys_read+0x140/0x240 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 x64_sys_call+0x96d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1472 [inline]
 free_pcp_prepare mm/page_alloc.c:1544 [inline]
 free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534
 free_unref_page+0xa2/0x550 mm/page_alloc.c:3616
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x6c/0x100 mm/page_alloc.c:5857
 pcpu_free_pages mm/percpu-vm.c:65 [inline]
 pcpu_depopulate_chunk+0x481/0x5a0 mm/percpu-vm.c:330
 pcpu_reclaim_populated mm/percpu.c:2195 [inline]
 pcpu_balance_workfn+0x2a7/0x1150 mm/percpu.c:2247
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Memory state around the buggy address:
 ffff88812816ef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812816f000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88812816f080: 00 fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00
                      ^
 ffff88812816f100: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff88812816f180: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop0): ext4_dx_csum_set:531: inode #2: comm syz.0.428: dir seems corrupt?  Run e2fsck -D.

Crashes (20):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/01 10:47 android13-5.15-lts 88c4075c39ed ce7952f4 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/03/31 08:43 android13-5.15-lts 5e1b899f19c3 d3999433 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/03/09 09:41 android13-5.15-lts 7d1f9b5c2ff5 163f510d .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/02/23 23:04 android13-5.15-lts 7d1f9b5c2ff5 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/02/22 15:05 android13-5.15-lts 058abb720bd1 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/02/22 12:38 android13-5.15-lts 058abb720bd1 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/02/18 17:56 android13-5.15-lts 058abb720bd1 c37c7249 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/02/13 04:56 android13-5.15-lts 058abb720bd1 b27c2402 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] [mounted in repro #3 (clean fs)] ci2-android-5-15 KASAN: slab-out-of-bounds Read in do_split
2025/05/25 03:12 android13-5.15-lts 4b77ae0e7f58 ed351ea7 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/03/25 20:57 android13-5.15-lts 7d1f9b5c2ff5 875573af .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/03/04 02:10 android13-5.15-lts 7d1f9b5c2ff5 c3901742 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/26 18:10 android13-5.15-lts 7d1f9b5c2ff5 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/25 17:50 android13-5.15-lts 7d1f9b5c2ff5 d34966d1 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/20 18:44 android13-5.15-lts 058abb720bd1 50668798 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/16 10:00 android13-5.15-lts 058abb720bd1 40a34ec9 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/16 06:56 android13-5.15-lts 058abb720bd1 40a34ec9 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/14 19:46 android13-5.15-lts 058abb720bd1 1022af74 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/14 11:14 android13-5.15-lts 058abb720bd1 d9a046cf .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/14 09:54 android13-5.15-lts 058abb720bd1 d9a046cf .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
2025/02/14 00:08 android13-5.15-lts 058abb720bd1 a98a8417 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in do_split
* Struck through repros no longer work on HEAD.