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KASAN: use-after-free Read in dx_insert_block

Status: upstream: reported C repro on 2025/02/08 09:19
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+d51f85ff27fd58389651@syzkaller.appspotmail.com
First crash: 62d, last: 13d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/02/08 lts (merge base) c63962be84ef C [report] KASAN: use-after-free Read in dx_insert_block
2025/03/23 upstream (ToT) 586de92313fc C [report] KASAN: slab-use-after-free Read in dx_insert_block
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/03/17 09:06 9m retest repro android14-6.1 report log
2025/03/17 09:06 11m retest repro android14-6.1 report log
2025/03/17 09:06 11m retest repro android14-6.1 report log
2025/03/17 09:06 9m retest repro android14-6.1 report log
2025/03/17 09:06 12m retest repro android14-6.1 report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in dx_insert_block+0xe8/0x260 fs/ext4/namei.c:1387
Read of size 157024 at addr ffff888123950028 by task syz-executor490/604

CPU: 1 PID: 604 Comm: syz-executor490 Not tainted 6.1.124-syzkaller-00004-g1ac09f5c0571 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0x158/0x4e0 mm/kasan/report.c:427
 kasan_report+0x13c/0x170 mm/kasan/report.c:531
 kasan_check_range+0x294/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block+0xe8/0x260 fs/ext4/namei.c:1387
 do_split+0x1e0e/0x2250 fs/ext4/namei.c:2080
 make_indexed_dir+0xeaf/0x1590 fs/ext4/namei.c:2392
 ext4_add_entry+0xbbf/0xed0 fs/ext4/namei.c:2504
 __ext4_link+0x4e9/0x790 fs/ext4/namei.c:3522
 ext4_link+0x1f3/0x290 fs/ext4/namei.c:3563
 vfs_link+0x645/0x7f0 fs/namei.c:4598
 do_linkat+0x34d/0x9f0 fs/namei.c:4669
 __do_sys_link fs/namei.c:4703 [inline]
 __se_sys_link fs/namei.c:4701 [inline]
 __x64_sys_link+0x86/0x90 fs/namei.c:4701
 x64_sys_call+0x282/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:87
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f07a0c586c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 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:00007f07a0c05168 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f07a0ce14a8 RCX: 00007f07a0c586c9
RDX: 0000000000000000 RSI: 0000400000000bc0 RDI: 0000400000001240
RBP: 00007f07a0ce14a0 R08: 00007f07a0c056c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f07a0ce14ac
R13: 000000000000000b R14: 00007ffd15ce9420 R15: 00007ffd15ce9508
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00048e5400 refcount:3 mapcount:1 mapping:ffff88810bd64950 index:0x1 pfn:0x123950
memcg:ffff888100336000
aops:def_blk_aops ino:700004
flags: 0x460000000032205e(referenced|uptodate|dirty|lru|workingset|private|mappedtodisk|unevictable|mlocked|zone=1)
raw: 460000000032205e dead000000000100 dead000000000001 ffff88810bd64950
raw: 0000000000000001 ffff8881219b49d8 0000000300000000 ffff888100336000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x152c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 607, tgid 607 (udevd), ts 292780240154, free_ts 281541373220
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x213/0x220 mm/page_alloc.c:2605
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2612
 get_page_from_freelist+0x2f41/0x2fc0 mm/page_alloc.c:4477
 __alloc_pages+0x234/0x610 mm/page_alloc.c:5775
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5807
 __folio_alloc_node include/linux/gfp.h:245 [inline]
 folio_alloc include/linux/gfp.h:274 [inline]
 filemap_alloc_folio include/linux/pagemap.h:513 [inline]
 page_cache_ra_unbounded+0x2cb/0x800 mm/readahead.c:260
 do_page_cache_ra mm/readahead.c:312 [inline]
 force_page_cache_ra mm/readahead.c:343 [inline]
 page_cache_sync_ra+0x394/0x450 mm/readahead.c:727
 page_cache_sync_readahead include/linux/pagemap.h:1257 [inline]
 filemap_get_pages mm/filemap.c:2688 [inline]
 filemap_read+0x7fa/0x2600 mm/filemap.c:2783
 blkdev_read_iter+0x3de/0x530 block/fops.c:613
 call_read_iter include/linux/fs.h:2268 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x801/0xae0 fs/read_write.c:470
 ksys_read+0x199/0x2c0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:621
 x64_sys_call+0x28/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1513 [inline]
 free_pcp_prepare mm/page_alloc.c:1587 [inline]
 free_unref_page_prepare+0x9f1/0xa00 mm/page_alloc.c:3526
 free_unref_page+0xb2/0x5c0 mm/page_alloc.c:3622
 __folio_put_small mm/swap.c:97 [inline]
 __folio_put+0xaa/0xe0 mm/swap.c:120
 folio_put include/linux/mm.h:1431 [inline]
 put_page include/linux/mm.h:1483 [inline]
 anon_pipe_buf_release+0x187/0x200 fs/pipe.c:138
 pipe_buf_release include/linux/pipe_fs_i.h:199 [inline]
 pipe_read+0x5a6/0x1040 fs/pipe.c:324
 call_read_iter include/linux/fs.h:2268 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x801/0xae0 fs/read_write.c:470
 ksys_read+0x199/0x2c0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:621
 x64_sys_call+0x28/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888123957f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888123957f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888123958000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888123958080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888123958100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================
EXT4-fs error (device loop4): ext4_dx_csum_set:531: inode #2: comm syz-executor490: dir seems corrupt?  Run e2fsck -D.

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/08 09:17 android14-6.1 1ac09f5c0571 ef44b750 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-6-1 KASAN: use-after-free Read in dx_insert_block
2025/03/27 11:59 android14-6.1 1c9aeb1ce34b 20510e88 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/03/02 17:56 android14-6.1 471a10d3af3b 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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/28 13:31 android14-6.1 fa3cc11118de 6a8fcbc4 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/28 01:31 android14-6.1 fa3cc11118de 6a8fcbc4 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/19 08:07 android14-6.1 a5f88b652947 9a14138f .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/17 08:44 android14-6.1 ccc915784332 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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/14 19:45 android14-6.1 ccc915784332 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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/12 02:32 android14-6.1 c93dcf3b5358 f2baddf5 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/10 06:33 android14-6.1 1ac09f5c0571 ef44b750 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/09 12:19 android14-6.1 1ac09f5c0571 ef44b750 .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/07 19:07 android14-6.1 09717ac61c87 53657d1b .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-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/06 16:50 android14-6.1 7658169f5f5f 577d049b .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-6-1 KASAN: use-after-free Read in dx_insert_block
2025/02/09 03:52 android14-6.1 1ac09f5c0571 ef44b750 .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-6-1 KASAN: slab-out-of-bounds Read in dx_insert_block
2025/02/08 05:16 android14-6.1 1ac09f5c0571 ef44b750 .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-6-1 KASAN: slab-out-of-bounds Read in dx_insert_block
* Struck through repros no longer work on HEAD.