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KASAN: out-of-bounds Read in ext4_ext_remove_space

Status: upstream: reported C repro on 2023/08/14 17:29
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+f0e6e46e2055146521a4@syzkaller.appspotmail.com
First crash: 459d, last: 13d
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 android14-6.1 (ToT) cfa154389a65 C [report] KASAN: out-of-bounds Read in ext4_ext_remove_space
2023/09/01 lts (merge base) b1644a0031cf 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-5-15 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport C error error 7 5d06h 436d 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 C 2 31d 407d 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 283d 457d 25/28 fixed on 2024/02/16 19:40
linux-5.15 KASAN: out-of-bounds Read in ext4_ext_remove_space origin:upstream missing-backport C error 3 10d 266d 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 done 4 57d 284d 0/3 upstream: reported C repro on 2024/01/03 15:27
▶ ▼ Last patch testing requests (7)
Created Duration User Patch Repo Result
2024/09/30 15:44 10m retest repro android14-6.1 report log
2024/09/30 15:44 11m retest repro android14-6.1 report log
2024/08/08 21:34 27m retest repro android14-6.1 report log
2024/07/22 10:11 13m retest repro android14-6.1 report log
2024/07/22 10:11 5m retest repro android14-6.1 report log
2024/07/22 10:11 59m retest repro android14-6.1 OK log
2024/04/28 01:29 10m 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 loop0): ext4_free_blocks:6208: comm syz-executor152: Freeing blocks not in datazone - block = 41, count = 1
EXT4-fs (loop0): Remounting filesystem read-only
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2713 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x1e16/0x4f50 fs/ext4/extents.c:2935
Read of size 18446744073709551604 at addr ffff88811fcf4018 by task syz-executor152/322

CPU: 1 PID: 322 Comm: syz-executor152 Not tainted 6.1.84-syzkaller-00135-gce6f9cab9edc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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
 ext4_ext_rm_leaf fs/ext4/extents.c:2713 [inline]
 ext4_ext_remove_space+0x1e16/0x4f50 fs/ext4/extents.c:2935
 ext4_punch_hole+0x794/0xc00 fs/ext4/inode.c:4129
 ext4_fallocate+0x318/0x1e90 fs/ext4/extents.c:4737
 vfs_fallocate+0x492/0x570 fs/open.c:324
 ksys_fallocate fs/open.c:347 [inline]
 __do_sys_fallocate fs/open.c:355 [inline]
 __se_sys_fallocate fs/open.c:353 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:353
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ffbdd835979
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:00007ffbdd7c2168 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007ffbdd8bd4b8 RCX: 00007ffbdd835979
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00007ffbdd8bd4b0 R08: 00007fff0b98ad27 R09: 0000000000000000
R10: 0000000000001a00 R11: 0000000000000246 R12: 00007ffbdd8bd4bc
R13: 0000000000000006 R14: 00007fff0b98ac40 R15: 00007fff0b98ad28
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00047f3d00 refcount:2 mapcount:0 mapping:ffff88810b7eb2d0 index:0x27 pfn:0x11fcf4
memcg:ffff88810f918000
aops:def_blk_aops ino:700000
flags: 0x5600000000002056(referenced|uptodate|lru|workingset|private|zone=1)
raw: 5600000000002056 ffff88810f91c190 ffffea00043f4548 ffff88810b7eb2d0
raw: 0000000000000027 ffff888120589930 00000002ffffffff ffff88810f918000
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 318, tgid 317 (syz-executor152), ts 41746345082, free_ts 41641447115
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x213/0x220 mm/page_alloc.c:2590
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2597
 get_page_from_freelist+0x27ea/0x2870 mm/page_alloc.c:4425
 __alloc_pages+0x3a1/0x780 mm/page_alloc.c:5714
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5746
 __folio_alloc_node include/linux/gfp.h:245 [inline]
 folio_alloc include/linux/gfp.h:274 [inline]
 filemap_alloc_folio include/linux/pagemap.h:507 [inline]
 __filemap_get_folio+0x827/0xae0 mm/filemap.c:1983
 pagecache_get_page+0x2f/0x110 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:648 [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_split_extent_at+0x863/0x11f0 fs/ext4/extents.c:3230
 ext4_split_extent+0x1bd/0x4e0 fs/ext4/extents.c:3331
 ext4_split_convert_extents fs/ext4/extents.c:3690 [inline]
 ext4_ext_handle_unwritten_extents fs/ext4/extents.c:3852 [inline]
 ext4_ext_map_blocks+0x2201/0x7390 fs/ext4/extents.c:4207
 ext4_map_blocks+0xa36/0x1ca0 fs/ext4/inode.c:651
 mpage_map_one_extent fs/ext4/inode.c:2423 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2476 [inline]
 ext4_writepages+0x17b5/0x3fd0 fs/ext4/inode.c:2844
 do_writepages+0x385/0x620 mm/page-writeback.c:2472
 filemap_fdatawrite_wbc+0x153/0x1b0 mm/filemap.c:402
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1498 [inline]
 free_pcp_prepare mm/page_alloc.c:1572 [inline]
 free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3498
 free_unref_page_list+0xf1/0x7b0 mm/page_alloc.c:3646
 release_pages+0xf7f/0xfe0 mm/swap.c:1063
 free_pages_and_swap_cache+0x8a/0xa0 mm/swap_state.c:314
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu mm/mmu_gather.c:261 [inline]
 tlb_finish_mmu+0x1e0/0x3f0 mm/mmu_gather.c:361
 unmap_region+0x2c1/0x310 mm/mmap.c:2405
 do_mas_align_munmap+0xd05/0x1400 mm/mmap.c:2672
 do_mas_munmap+0x23e/0x2b0 mm/mmap.c:2730
 __vm_munmap+0x263/0x3a0 mm/mmap.c:3020
 __do_sys_munmap mm/mmap.c:3046 [inline]
 __se_sys_munmap mm/mmap.c:3042 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3042
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88811fcf3f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811fcf3f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811fcf4000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                            ^
 ffff88811fcf4080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811fcf4100: 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:4497: comm syz-executor152: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0) in ext4_reserve_inode_write:5870: Corrupt filesystem
EXT4-fs error (device loop0): __ext4_ext_dirty:202: inode #18: comm syz-executor152: mark_inode_dirty error
EXT4-fs error (device loop0): __ext4_get_inode_loc:4497: comm syz-executor152: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0) in ext4_reserve_inode_write:5870: Corrupt filesystem
EXT4-fs error (device loop0): ext4_punch_hole:4142: inode #18: comm syz-executor152: mark_inode_dirty error

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