syzbot


KASAN: out-of-bounds Read in ext4_ext_remove_space

Status: upstream: reported C repro on 2023/08/04 22:38
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+b08e3d059329c5bfbfdb@syzkaller.appspotmail.com
First crash: 372d, last: 4d11h
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
Bug presence (4)
Date Name Commit Repro Result
2024/04/13 android13-5.15-lts (ToT) 993bed180178 C [report] KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/09/01 lts (merge base) f6f7927ac664 C [report] KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/09/01 upstream (ToT) 99d99825fc07 C [report] KASAN: out-of-bounds Read in ext4_ext_remove_space
2024/04/13 upstream (ToT) 7efd0a74039f C Didn't crash
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: out-of-bounds Read in ext4_ext_remove_space C 2 30d 324d 0/2 upstream: reported C repro on 2023/09/02 13:17
upstream KASAN: out-of-bounds Read in ext4_ext_remove_space ext4 C error done 8 200d 375d 26/27 fixed on 2024/02/16 19:40
android-6-1 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport C error error 6 1d01h 343d 0/2 upstream: reported C repro on 2023/08/14 17:29
linux-5.15 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport C error 3 57d 183d 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 C 2 3d11h 201d 0/3 upstream: reported C repro on 2024/01/03 15:27
Last patch testing requests (5)
Created Duration User Patch Repo Result
2024/07/07 03:26 23m retest repro android13-5.15-lts report log
2024/06/18 20:20 17m retest repro android13-5.15-lts report log
2024/04/28 03:11 11m retest repro android13-5.15-lts report log
2024/03/26 07:48 10m retest repro android13-5.15-lts report log
2024/03/08 04:40 11m retest repro android13-5.15-lts report log
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2024/05/30 20:00 6m bisect fix android13-5.15-lts error job log
2023/10/20 03:00 35m bisect fix android13-5.15-lts OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2735 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x2149/0x4a60 fs/ext4/extents.c:2957
Read of size 18446744073709551544 at addr ffff88811aee3054 by task syz-executor347/307

CPU: 0 PID: 307 Comm: syz-executor347 Not tainted 5.15.120-syzkaller-00229-g748fd0d9ca0f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:444
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 ext4_ext_rm_leaf fs/ext4/extents.c:2735 [inline]
 ext4_ext_remove_space+0x2149/0x4a60 fs/ext4/extents.c:2957
 ext4_punch_hole+0x794/0xbf0 fs/ext4/inode.c:4129
 ext4_fallocate+0x30c/0x1f10 fs/ext4/extents.c:4711
 vfs_fallocate+0x492/0x570 fs/open.c:309
 do_vfs_ioctl+0x2238/0x2a80 fs/ioctl.c:853
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x99/0x190 fs/ioctl.c:860
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:860
 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+0x61/0xcb
RIP: 0033:0x7f9520578e19
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 18 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:00007f9518154218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f95206006d8 RCX: 00007f9520578e19
RDX: 0000000020000080 RSI: 000000004030582b RDI: 0000000000000004
RBP: 00007f95206006d0 R08: 00007ffe005087d7 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f95205cd578
R13: 000000000000000b R14: 00007ffe005086f0 R15: 6f6f6c2f7665642f
 </TASK>

The buggy address belongs to the page:
page:ffffea00046bb8c0 refcount:2 mapcount:0 mapping:ffff888109192c98 index:0x3a pfn:0x11aee3
memcg:ffff8881001f8000
aops:def_blk_aops ino:700000
flags: 0x4000000000002036(referenced|uptodate|lru|active|private|zone=1)
raw: 4000000000002036 ffffea00046da308 ffffea00046da408 ffff888109192c98
raw: 000000000000003a ffff88811bd1bb28 00000002ffffffff ffff8881001f8000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 304, ts 23868189950, free_ts 23787864920
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2600
 prep_new_page mm/page_alloc.c:2606 [inline]
 get_page_from_freelist+0x2ed2/0x2f90 mm/page_alloc.c:4474
 __alloc_pages+0x206/0x5e0 mm/page_alloc.c:5765
 __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]
 pagecache_get_page+0xb18/0xeb0 mm/filemap.c:1940
 find_or_create_page include/linux/pagemap.h:418 [inline]
 grow_dev_page fs/buffer.c:949 [inline]
 grow_buffers fs/buffer.c:1014 [inline]
 __getblk_slow fs/buffer.c:1041 [inline]
 __getblk_gfp+0x21e/0x7c0 fs/buffer.c:1336
 sb_getblk_gfp include/linux/buffer_head.h:368 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1328 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1429 [inline]
 ext4_ext_insert_extent+0xf7a/0x4b10 fs/ext4/extents.c:2099
 ext4_ext_map_blocks+0x1c61/0x7250 fs/ext4/extents.c:4308
 ext4_map_blocks+0xaa7/0x1e30 fs/ext4/inode.c:646
 _ext4_get_block+0x23b/0x660 fs/ext4/inode.c:803
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:820
 ext4_block_write_begin+0x5ea/0x12a0 fs/ext4/inode.c:1088
 ext4_write_begin+0x6bc/0x13d0
 ext4_da_write_begin+0x4a2/0xc30 fs/ext4/inode.c:2986
 generic_perform_write+0x2bc/0x5a0 mm/filemap.c:3833
 ext4_buffered_write_iter+0x48a/0x610 fs/ext4/file.c:270
 ext4_file_write_iter+0x443/0x1c80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1467 [inline]
 free_pcp_prepare mm/page_alloc.c:1539 [inline]
 free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3523
 free_unref_page_list+0x14b/0xa60 mm/page_alloc.c:3660
 release_pages+0x1310/0x1370 mm/swap.c:1009
 __pagevec_release+0x84/0x100 mm/swap.c:1029
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x604/0x1560 mm/shmem.c:965
 shmem_truncate_range mm/shmem.c:1064 [inline]
 shmem_evict_inode+0x215/0x9d0 mm/shmem.c:1146
 evict+0x2a3/0x630 fs/inode.c:587
 iput_final fs/inode.c:1663 [inline]
 iput+0x63b/0x7e0 fs/inode.c:1689
 dentry_unlink_inode+0x34f/0x440 fs/dcache.c:376
 __dentry_kill+0x447/0x660 fs/dcache.c:582
 dentry_kill+0xc0/0x2a0
 dput+0x165/0x320 fs/dcache.c:888
 __fput+0x662/0x910 fs/file_table.c:288
 ____fput+0x15/0x20 fs/file_table.c:308
 task_work_run+0x129/0x190 kernel/task_work.c:164
 ptrace_notify+0x29e/0x350 kernel/signal.c:2383

Memory state around the buggy address:
 ffff88811aee2f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811aee2f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88811aee3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff88811aee3080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811aee3100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop0): __ext4_get_inode_loc:4350: comm syz-executor347: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0) in ext4_reserve_inode_write:5830: Corrupt filesystem
EXT4-fs error (device loop0): ext4_punch_hole:4142: inode #16: comm syz-executor347: mark_inode_dirty error

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/08/04 22:28 android13-5.15-lts 748fd0d9ca0f cdae481e .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/09/06 00:23 android13-5.15-lts 1317bd27a72f 0b6286dc .config console log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/07/17 12:33 android13-5.15-lts 879959450ec7 35d9ecc5 .config console log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
2024/07/19 01:37 android13-5.15-lts db06c48ab67e ee4e11c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
2024/05/31 09:46 android13-5.15-lts 424f92bcbe8f 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/08/04 22:09 android13-5.15-lts 748fd0d9ca0f cdae481e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space
* Struck through repros no longer work on HEAD.