syzbot


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: 320d, last: 30d
Cause 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 4 30d 297d 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 1 34d 268d 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 144d 318d 26/26 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 3 1d16h 127d 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 1 4d18h 145d 0/3 upstream: reported C repro on 2024/01/03 15:27
Last patch testing requests (4)
Created Duration User Patch Repo Result
2024/04/28 01:29 10m retest repro android14-6.1 report log
2024/04/28 01:29 18m retest repro android14-6.1 report log
2024/01/27 12:15 11m retest repro android14-6.1 report log
2024/01/27 12:15 17m retest repro android14-6.1 report log
Fix bisection attempts (6)
Created Duration User Patch Repo Result
2024/04/04 08:22 50m bisect fix android14-6.1 job log (0) log
2024/03/05 06:32 58m bisect fix android14-6.1 job log (0) log
2024/01/13 10:49 46m bisect fix android14-6.1 job log (0) log
marked invalid by web-security-scanner@google.com
2023/12/13 09:55 1h12m bisect fix android14-6.1 job log (0) log
2023/10/29 17:51 42m bisect fix android14-6.1 job log (0) log
2023/09/28 17:15 1h01m bisect fix android14-6.1 job log (0) log

Sample crash report:
EXT4-fs error (device loop0): ext4_read_block_bitmap_nowait:438: comm syz-executor348: Invalid block bitmap block 0 in block_group 0
EXT4-fs (loop0): Remounting filesystem read-only
EXT4-fs error (device loop0) 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 ffff88812095e054 by task syz-executor348/311

CPU: 1 PID: 311 Comm: syz-executor348 Not tainted 6.1.25-syzkaller-00011-gd7dacaa439c7 #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 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: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: 0033:0x7fa52c38be19
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:00007fa523f67218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa52c4136d8 RCX: 00007fa52c38be19
RDX: 0000000020000080 RSI: 000000004030582b RDI: 0000000000000004
RBP: 00007fa52c4136d0 R08: 00007ffe5a02a957 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa52c3e0578
R13: 000000000000000b R14: 00007ffe5a02a870 R15: 6f6f6c2f7665642f
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004825780 refcount:2 mapcount:0 mapping:ffff88810b8e1c50 index:0x3a pfn:0x12095e
memcg:ffff88810031e000
aops:def_blk_aops ino:700000
flags: 0x4e00000000002056(referenced|uptodate|lru|workingset|private|zone=1)
raw: 4e00000000002056 ffffea00047a36c8 ffffea0004266648 ffff88810b8e1c50
raw: 000000000000003a ffff88811fd0b3f0 00000002ffffffff ffff88810031e000
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 308, tgid 307 (syz-executor348), ts 22218821051, free_ts 15091448006
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x213/0x220 mm/page_alloc.c:2582
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2589
 get_page_from_freelist+0x2762/0x27f0 mm/page_alloc.c:4387
 __alloc_pages+0x3a1/0x780 mm/page_alloc.c:5664
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5696
 __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
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1494 [inline]
 free_pcp_prepare mm/page_alloc.c:1568 [inline]
 free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3486
 free_unref_page_list+0xf6/0x6c0 mm/page_alloc.c:3628
 release_pages+0xf7f/0xfe0 mm/swap.c:1055
 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:2383
 do_mas_align_munmap+0xd05/0x1400 mm/mmap.c:2645
 do_mas_munmap+0x23e/0x2b0 mm/mmap.c:2703
 __vm_munmap+0x263/0x3a0 mm/mmap.c:2993
 __do_sys_munmap mm/mmap.c:3019 [inline]
 __se_sys_munmap mm/mmap.c:3015 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3015
 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:
 ffff88812095df00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812095df80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812095e000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff88812095e080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812095e100: 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:4492: comm syz-executor348: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0) in ext4_reserve_inode_write:5841: Corrupt filesystem
EXT4-fs error (device loop0): ext4_punch_hole:4137: inode #16: comm syz-executor348: mark_inode_dirty error

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
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.