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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: 50d, last: 4d13h
▶ ▼ 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 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 BUG: unable to handle kernel paging request in do_split C error 25 1d09h 238d 0/2 upstream: reported C repro on 2024/08/09 00:52
linux-6.1 KASAN: use-after-free Read in do_split 1 148d 148d 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 C inconclusive 17 266d 279d 27/28 fixed on 2024/08/14 03:44
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/03/23 20:04 10m retest repro android13-5.15-lts report log
2025/03/23 20:04 16m retest repro android13-5.15-lts report log
2025/03/23 20:04 12m retest repro android13-5.15-lts report log
2025/03/23 20:04 7m retest repro android13-5.15-lts report log
2025/03/23 20:04 12m 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+0x1f31/0x24e0 fs/ext4/namei.c:2080
Read of size 157024 at addr ffff88812bf7e028 by task syz.0.974/3462

CPU: 1 PID: 3462 Comm: syz.0.974 Not tainted 5.15.178-syzkaller-00034-g5e1b899f19c3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:444
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block fs/ext4/namei.c:1387 [inline]
 do_split+0x1f31/0x24e0 fs/ext4/namei.c:2080
 make_indexed_dir+0xeb7/0x15a0 fs/ext4/namei.c:2392
 ext4_add_entry+0xde2/0x12b0 fs/ext4/namei.c:2504
 __ext4_link+0x4e9/0x790 fs/ext4/namei.c:3536
 ext4_link+0x1f3/0x290 fs/ext4/namei.c:3577
 vfs_link+0x645/0x7f0 fs/namei.c:4557
 do_linkat+0x34d/0x9f0 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+0x282/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:87
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f750df34169
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:00007f750d9a6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f750e14cfa0 RCX: 00007f750df34169
RDX: 0000000000000000 RSI: 0000200000000bc0 RDI: 0000200000001240
RBP: 00007f750dfb52a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f750e14cfa0 R15: 00007ffea00db968
 </TASK>

The buggy address belongs to the page:
page:ffffea0004afdf80 refcount:3 mapcount:1 mapping:ffff88810933d358 index:0x1 pfn:0x12bf7e
memcg:ffff88810024c000
aops:def_blk_aops ino:700000
flags: 0x400000000032201e(referenced|uptodate|dirty|lru|private|mappedtodisk|unevictable|mlocked|zone=1)
raw: 400000000032201e ffff888100247040 ffffea0004872508 ffff88810933d358
raw: 0000000000000001 ffff8881110f3150 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 2746, ts 329701755953, free_ts 329680141643
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4485
 __alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5780
 __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+0x334/0xa50 mm/readahead.c:227
 do_page_cache_ra mm/readahead.c:280 [inline]
 force_page_cache_ra+0x3c0/0x420 mm/readahead.c:312
 page_cache_sync_ra+0x2d5/0x4d0 mm/readahead.c:590
 page_cache_sync_readahead include/linux/pagemap.h:831 [inline]
 filemap_get_pages mm/filemap.c:2560 [inline]
 filemap_read+0x7cd/0x2600 mm/filemap.c:2645
 generic_file_read_iter+0xae/0x420 mm/filemap.c:2805
 blkdev_read_iter+0x135/0x190 block/fops.c:560
 call_read_iter include/linux/fs.h:2198 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0xa81/0xd40 fs/read_write.c:485
 ksys_read+0x199/0x2c0 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+0x28/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 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+0x7c8/0x7d0 mm/page_alloc.c:3534
 free_unref_page+0xe8/0x750 mm/page_alloc.c:3616
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x61/0xf0 mm/page_alloc.c:5856
 __free_slab+0xec/0x1d0 mm/slub.c:2020
 free_slab mm/slub.c:2035 [inline]
 discard_slab+0x29/0x40 mm/slub.c:2041
 __slab_free+0x205/0x290 mm/slub.c:3426
 do_slab_free mm/slub.c:3509 [inline]
 ___cache_free+0x109/0x120 mm/slub.c:3530
 qlink_free+0x4d/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x44/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x15a/0x180 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:443
 kasan_slab_alloc include/linux/kasan.h:217 [inline]
 slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:550
 slab_alloc_node mm/slub.c:3240 [inline]
 slab_alloc mm/slub.c:3250 [inline]
 kmem_cache_alloc+0xf5/0x250 mm/slub.c:3255
 kmem_cache_alloc_node include/linux/slab.h:474 [inline]
 __alloc_skb+0xbe/0x550 net/core/skbuff.c:416
 alloc_skb include/linux/skbuff.h:1183 [inline]
 nlmsg_new include/net/netlink.h:953 [inline]
 rtmsg_ifinfo_build_skb+0x7f/0x180 net/core/rtnetlink.c:3881
 unregister_netdevice_many+0xea2/0x17c0 net/core/dev.c:11122

Memory state around the buggy address:
 ffff88812bf7ef00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812bf7ef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88812bf7f000: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
                                                          ^
 ffff88812bf7f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88812bf7f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
==================================================================
EXT4-fs error (device loop0): ext4_dx_csum_set:531: inode #2: comm syz.0.974: dir seems corrupt?  Run e2fsck -D.

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
2025/03/25 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.