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KASAN: out-of-bounds Read in ext4_ext_remove_space

Status: upstream: reported C repro on 2023/09/02 13:17
Reported-by: syzbot+346920c4ba6752340f29@syzkaller.appspotmail.com
First crash: 881d, last: 11d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport 24 C error error 33 7h51m 910d 0/2 upstream: reported C repro on 2023/08/04 22:38
upstream KASAN: out-of-bounds Read in ext4_ext_remove_space ext4 17 C error done 8 757d 931d 25/29 fixed on 2024/02/16 19:40
android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space missing-backport 17 C error error 6 468d 900d 0/2 auto-obsoleted due to no activity on 2025/01/27 17:01
linux-5.15 KASAN: out-of-bounds Read in ext4_ext_remove_space missing-backport origin:upstream 17 C done 5 44d 740d 0/3 upstream: reported C repro on 2024/01/21 16:07
linux-6.1 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport 19 C done 9 46d 758d 0/3 upstream: reported C repro on 2024/01/03 15:27
android-6-1 KASAN: use-after-free Read in ext4_ext_remove_space origin:lts 19 C error 8 12d 194d 0/2 upstream: reported C repro on 2025/07/20 13:48
upstream KASAN: slab-use-after-free Read in ext4_ext_remove_space ext4 19 C error 44 4d10h 305d 0/29 upstream: reported C repro on 2025/03/31 11:15
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/01/06 18:52 7m retest repro android13-5.10-lts report log
2026/01/06 18:52 5m retest repro android13-5.10-lts report log
2026/01/06 18:52 7m retest repro android13-5.10-lts report log
2026/01/06 18:52 6m retest repro android13-5.10-lts report log
2026/01/06 18:52 40m retest repro android13-5.10-lts report log
2025/11/26 02:02 13m retest repro android13-5.10-lts report log
2025/11/05 17:04 10m retest repro android13-5.10-lts report log
2025/10/18 17:27 8m retest repro android13-5.10-lts report log
2025/10/18 17:27 5m retest repro android13-5.10-lts report log
2025/10/18 17:27 14m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (11)
Created Duration User Patch Repo Result
2024/10/15 01:57 0m bisect fix android13-5.10-lts error job log
2024/08/29 08:21 1h10m bisect fix android13-5.10-lts OK (0) job log log
2024/07/28 05:51 1h00m bisect fix android13-5.10-lts OK (0) job log log
2024/05/29 16:16 37m bisect fix android13-5.10-lts OK (0) job log log
2024/04/24 01:12 1h43m bisect fix android13-5.10-lts OK (0) job log log
2024/03/24 10:22 36m bisect fix android13-5.10-lts OK (0) job log log
2024/02/23 07:48 1h47m bisect fix android13-5.10-lts OK (0) job log log
2024/01/20 07:40 40m bisect fix android13-5.10-lts OK (0) job log log
2023/12/19 08:27 45m bisect fix android13-5.10-lts OK (0) job log log
2023/11/19 03:02 39m bisect fix android13-5.10-lts OK (0) job log log
2023/10/18 11:52 35m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2712 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x258d/0x4920 fs/ext4/extents.c:2934
Read of size 18446744073709551568 at addr ffff88811167346c by task syz.6.403/2590

CPU: 1 PID: 2590 Comm: syz.6.403 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 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
 ext4_ext_rm_leaf fs/ext4/extents.c:2712 [inline]
 ext4_ext_remove_space+0x258d/0x4920 fs/ext4/extents.c:2934
 ext4_punch_hole+0x6f8/0xad0 fs/ext4/inode.c:4223
 ext4_fallocate+0x271/0x1a70 fs/ext4/extents.c:4758
 vfs_fallocate+0x4b4/0x590 fs/open.c:310
 madvise_remove mm/madvise.c:880 [inline]
 madvise_vma_behavior mm/madvise.c:904 [inline]
 madvise_walk_vmas mm/madvise.c:1131 [inline]
 do_madvise+0x12cf/0x1df0 mm/madvise.c:1308
 __do_sys_madvise mm/madvise.c:1322 [inline]
 __se_sys_madvise mm/madvise.c:1320 [inline]
 __x64_sys_madvise+0xa9/0xc0 mm/madvise.c:1320
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f50c1b51749
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:00007f50c19a0038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f50c1da8090 RCX: 00007f50c1b51749
RDX: 0000000000000009 RSI: 0000000000600003 RDI: 0000200000000000
RBP: 00007f50c1bd5f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50c1da8128 R14: 00007f50c1da8090 R15: 00007fffa693ae58

The buggy address belongs to the page:
page:ffffea0004459cc0 refcount:2 mapcount:0 mapping:ffff888110762490 index:0x40 pfn:0x111673
aops:def_blk_aops ino:0
flags: 0x400000000002203e(referenced|uptodate|dirty|lru|active|private|mappedtodisk)
raw: 400000000002203e ffffea000461a5c8 ffffea000452dc88 ffff888110762490
raw: 0000000000000040 ffff88810d27e690 00000002ffffffff ffff888100142000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888100142000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 458, ts 357657221607, free_ts 357554310447
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 __page_cache_alloc include/linux/pagemap.h:290 [inline]
 page_cache_ra_unbounded+0x2c8/0x7d0 mm/readahead.c:226
 do_page_cache_ra mm/readahead.c:277 [inline]
 force_page_cache_ra+0x3a9/0x400 mm/readahead.c:308
 page_cache_sync_ra+0x237/0x2a0 mm/readahead.c:582
 page_cache_sync_readahead include/linux/pagemap.h:837 [inline]
 generic_file_buffered_read+0x55b/0x2730 mm/filemap.c:2250
 generic_file_read_iter+0x116/0x560 mm/filemap.c:2568
 blkdev_read_iter+0x12f/0x160 fs/block_dev.c:1956
 call_read_iter include/linux/fs.h:2060 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x874/0xa10 fs/read_write.c:496
 ksys_read+0x140/0x240 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:642
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page mm/page_alloc.c:5429 [inline]
 __free_pages+0x14b/0x380 mm/page_alloc.c:5440
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x15f/0x190 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x111/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc+0x183/0x330 mm/slub.c:4034
 __kmalloc_node include/linux/slab.h:421 [inline]
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x88/0x130 mm/util.c:612
 kvmalloc include/linux/mm.h:833 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x1fc/0xd30 fs/seq_file.c:210
 kernfs_fop_read_iter+0x147/0x470 fs/kernfs/file.c:241

Memory state around the buggy address:
 ffff888111673300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888111673380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888111673400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                          ^
 ffff888111673480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888111673500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (42):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/07 08:57 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/09/02 13:14 android13-5.10-lts c8ca447a86a2 696ea0d2 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: out-of-bounds Read in ext4_ext_remove_space
2025/12/02 02:08 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/10/22 14:41 android13-5.10-lts 2ece552169c2 252fbbad .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/07 07:19 android13-5.10-lts 48647f2c6800 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/07 06:12 android13-5.10-lts 48647f2c6800 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/07 05:10 android13-5.10-lts 48647f2c6800 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/06/04 06:00 android13-5.10-lts cf6ed0f1511d a30356b7 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2024/06/08 18:04 android13-5.10-lts d3c4d815bf09 82c05ab8 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: out-of-bounds Read in ext4_ext_remove_space
2025/03/15 19:45 android13-5.10-lts fc9aa81462ee e2826670 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_ext_remove_space
2025/03/14 07:04 android13-5.10-lts 3f5f2283d684 e2826670 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_ext_remove_space
2026/01/19 15:55 android13-5.10-lts e253c52bbdfc a9fc5226 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2026/01/19 03:05 android13-5.10-lts e253c52bbdfc 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2026/01/19 01:14 android13-5.10-lts e253c52bbdfc 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/23 09:21 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/20 03:19 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/20 03:18 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/20 03:18 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/13 03:58 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/12 22:09 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/12 11:41 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/12 06:16 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/11 17:14 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/11 02:45 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/10 08:23 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/07 21:09 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/06 18:00 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/12/06 17:58 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/28 19:59 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/28 04:32 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/28 04:05 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/28 03:52 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/26 22:22 android13-5.10-lts 9286af17ed5f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/11/11 08:32 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/10/18 23:27 android13-5.10-lts 2ece552169c2 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/20 01:13 android13-5.10-lts 911f602c2237 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/18 16:29 android13-5.10-lts 911f602c2237 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/14 21:49 android13-5.10-lts 911f602c2237 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/09/07 20:20 android13-5.10-lts 48647f2c6800 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/07/07 16:05 android13-5.10-lts 59e9a7228857 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
2025/03/31 21:01 android13-5.10-lts 094fc3778d6b d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_ext_remove_space
2025/01/07 12:03 android13-5.10-lts 49e8ba0a684f f3558dbf .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_ext_remove_space
* Struck through repros no longer work on HEAD.