KASAN: out-of-bounds Read in ext4_ext_remove_space

Status: auto-obsoleted due to no activity on 2025/01/27 17:01
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+f0e6e46e2055146521a4@syzkaller.appspotmail.com
First crash: 1125d, last: 660d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2024/10/31 lts (merge base) aa4cd140bba5 syz Didn't crash
2024/10/31 upstream (ToT) 0fc810ae3ae1 syz Didn't crash
▶ ▼ Similar bugs (8)
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 22 syz, C error error 54 88d 1101d 0/2 upstream: reported C repro on 2023/08/04 22:38
android-5-10 KASAN: out-of-bounds Read in ext4_ext_remove_space 22 syz, C error 59 96d 1073d 0/2 upstream: reported C repro on 2023/09/02 13:17
upstream KASAN: out-of-bounds Read in ext4_ext_remove_space ext4 17 syz, C error done 8 949d 1123d 25/29 fixed on 2024/02/16 19:40
linux-5.15 KASAN: out-of-bounds Read in ext4_ext_remove_space missing-backport origin:upstream 17 syz, C done 5 89d 932d 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 syz, C done 35 130d 950d 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 syz, C error 13 70d 386d 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 syz, C error 73 139d 497d 29/29 fixed on 2026/05/21 07:50
linux-6.6 KASAN: use-after-free Read in ext4_ext_remove_space 19 1 159d 159d 0/2 auto-obsoleted due to no activity on 2026/06/12 03:57
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/10/19 16:47 13m retest repro android14-6.1 report log
▶ ▼ Fix bisection attempts (7)
Created Duration User Patch Repo Result
2024/05/30 17:45 7m bisect fix android14-6.1 error job log
2024/04/04 08:22 50m bisect fix android14-6.1 OK (0) job log log
2024/03/05 06:32 58m bisect fix android14-6.1 OK (0) job log log
2024/01/13 10:49 46m bisect fix android14-6.1 OK (0) job log log
marked invalid by web-security-scanner@google.com
2023/12/13 09:55 1h12m bisect fix android14-6.1 OK (0) job log log
2023/10/29 17:51 42m bisect fix android14-6.1 OK (0) job log log
2023/09/28 17:15 1h01m bisect fix android14-6.1 OK (0) job log log

Sample crash report:
EXT4-fs error (device loop5) in ext4_mb_clear_bb:6077: Corrupt filesystem
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2737 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x1e16/0x4f50 fs/ext4/extents.c:2959
Read of size 18446744073709551544 at addr ffff888129543054 by task syz-executor.5/4453

CPU: 0 PID: 4453 Comm: syz-executor.5 Not tainted 6.1.25-syzkaller-00012-gf3c6324daa33 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
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:284 [inline]
 print_report+0x158/0x4e0 mm/kasan/report.c:395
 kasan_report+0x13c/0x170 mm/kasan/report.c:495
 kasan_check_range+0x294/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 ext4_ext_rm_leaf fs/ext4/extents.c:2737 [inline]
 ext4_ext_remove_space+0x1e16/0x4f50 fs/ext4/extents.c:2959
 ext4_punch_hole+0x794/0xc00 fs/ext4/inode.c:4124
 ext4_fallocate+0x318/0x1e90 fs/ext4/extents.c:4708
 vfs_fallocate+0x492/0x570 fs/open.c:324
 do_vfs_ioctl+0x2150/0x29a0 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x99/0x190 fs/ioctl.c:856
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1f9a27cb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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:00007f1f91a1e0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1f9a39c050 RCX: 00007f1f9a27cb29
RDX: 0000000020000080 RSI: 000000004030582b RDI: 0000000000000004
RBP: 00007f1f9a2c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f1f9a39c050 R15: 00007ffd87a46958
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004a550c0 refcount:2 mapcount:0 mapping:ffff88810054c950 index:0x3a pfn:0x129543
memcg:ffff888111d4e000
aops:def_blk_aops ino:700005
flags: 0x4e00000000002056(referenced|uptodate|lru|workingset|private|zone=1)
raw: 4e00000000002056 ffffea0004a77948 ffffea0004637b88 ffff88810054c950
raw: 000000000000003a ffff88811fb01dc8 00000002ffffffff ffff888111d4e000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 4438, tgid 4434 (syz-executor.5), ts 127005567422, free_ts 126075053118
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x213/0x220 mm/page_alloc.c:2581
 prep_new_page mm/page_alloc.c:2588 [inline]
 get_page_from_freelist+0x276c/0x2850 mm/page_alloc.c:4385
 __alloc_pages+0x3a1/0x780 mm/page_alloc.c:5662
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5694
 __folio_alloc_node include/linux/gfp.h:245 [inline]
 folio_alloc include/linux/gfp.h:274 [inline]
 filemap_alloc_folio include/linux/pagemap.h:474 [inline]
 __filemap_get_folio+0x6c0/0x970 mm/filemap.c:1976
 pagecache_get_page+0x2f/0x110 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:615 [inline]
 grow_dev_page fs/buffer.c:989 [inline]
 grow_buffers fs/buffer.c:1054 [inline]
 __getblk_slow fs/buffer.c:1081 [inline]
 __getblk_gfp+0x205/0x7d0 fs/buffer.c:1376
 sb_getblk_gfp include/linux/buffer_head.h:363 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1334 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1435 [inline]
 ext4_ext_insert_extent+0xfd2/0x4e00 fs/ext4/extents.c:2102
 ext4_ext_map_blocks+0x1c31/0x71e0 fs/ext4/extents.c:4308
 ext4_map_blocks+0xa42/0x1ce0 fs/ext4/inode.c:651
 _ext4_get_block+0x23b/0x660 fs/ext4/inode.c:808
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:825
 ext4_block_write_begin+0x55e/0x1200 fs/ext4/inode.c:1098
 ext4_write_begin+0x5e0/0xfb0
 ext4_da_write_begin+0x2ff/0x920 fs/ext4/inode.c:2987
 generic_perform_write+0x2f9/0x5c0 mm/filemap.c:3765
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1493 [inline]
 free_pcp_prepare mm/page_alloc.c:1567 [inline]
 free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3484
 free_unref_page_list+0xf6/0x6c0 mm/page_alloc.c:3626
 release_pages+0xf7f/0xfe0 mm/swap.c:1055
 __pagevec_release+0x84/0x100 mm/swap.c:1075
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 truncate_inode_pages_range+0x1d1/0x1020 mm/truncate.c:375
 truncate_pagecache_range+0xa1/0xb0 mm/truncate.c:878
 ext4_punch_hole+0x482/0xc00 fs/ext4/inode.c:4086
 ext4_fallocate+0x318/0x1e90 fs/ext4/extents.c:4708
 vfs_fallocate+0x492/0x570 fs/open.c:324
 do_vfs_ioctl+0x2150/0x29a0 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x99/0x190 fs/ioctl.c:856
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff888129542f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888129542f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888129543000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff888129543080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888129543100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop5): __ext4_get_inode_loc:4492: comm syz-executor.5: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop5) in ext4_reserve_inode_write:5841: Corrupt filesystem
EXT4-fs error (device loop5): ext4_punch_hole:4137: inode #16: comm syz-executor.5: mark_inode_dirty error

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/12 09:11 android14-6.1 f3c6324daa33 2f19aa4f .config console log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
2024/07/08 08:26 android14-6.1 ce6f9cab9edc 2a40360c .config strace log report syz / log C [mounted in repro] ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
2024/06/30 05:45 android14-6.1 76d91af9daec 757f06b1 .config console log report info ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/08/14 17:27 android14-6.1 d7dacaa439c7 39990d51 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/07/30 21:23 android14-6.1 d3b37a712ab7 2a0d0f29 .config console log report syz [mounted in repro] ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/07/30 16:52 android14-6.1 d3b37a712ab7 2a0d0f29 .config console log report info ci2-android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space
* Struck through repros no longer work on HEAD.