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KASAN: use-after-free Read in ext4_find_extent

Status: upstream: reported C repro on 2022/12/26 07:59
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+212b805f83aa4e82c10a@syzkaller.appspotmail.com
First crash: 876d, last: 11h59m
Cause bisection: failed (error log, bisect log)
  
Fix bisection the fix commit could be any of (bisect log):
  003c389455eb Merge 5.10.160 into android12-5.10-lts
  bf760358eac3 Merge branch 'android12-5.10' into android12-5.10-lts
   
▶ ▼ Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-54 KASAN: use-after-free Read in ext4_find_extent C 1 59d 73d 0/2 upstream: reported C repro on 2025/02/13 21:05
android-6-1 KASAN: use-after-free Read in ext4_find_extent missing-backport C error done 3 183d 680d 0/2 auto-obsoleted due to no activity on 2025/02/04 04:57
linux-5.15 KASAN: use-after-free Read in ext4_find_extent origin:lts-only C inconclusive 5 65d 649d 0/3 upstream: reported C repro on 2023/07/19 14:49
upstream KASAN: use-after-free Read in ext4_find_extent ext4 2 1286d 1347d 0/28 auto-closed as invalid on 2022/02/17 05:19
linux-6.1 KASAN: use-after-free Read in ext4_find_extent origin:upstream missing-backport C done 1 364d 587d 0/3 upstream: reported C repro on 2023/09/19 00:11
android-5-15 KASAN: use-after-free Read in ext4_find_extent ext4 origin:lts C error 11 14d 854d 0/2 upstream: reported C repro on 2022/12/26 07:59
upstream KASAN: use-after-free Read in ext4_find_extent (2) ext4 C error 2 724d 849d 22/28 fixed on 2023/06/08 14:41
upstream KASAN: use-after-free Read in ext4_find_extent (4) ext4 C done 33 7h09m 118d 0/28 upstream: reported C repro on 2024/12/30 20:06
upstream KASAN: use-after-free Read in ext4_find_extent (3) prio:low ext4 C error done 31 489d 671d 25/28 fixed on 2024/01/30 23:26
android-54 KASAN: slab-out-of-bounds Read in ext4_find_extent ext4 C 1 668d 854d 0/2 auto-obsoleted due to no activity on 2023/10/08 03:20
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2025/04/09 17:18 7m retest repro android13-5.10-lts report log
2025/04/09 17:18 7m retest repro android13-5.10-lts report log
2025/04/09 17:18 1h05m retest repro android13-5.10-lts report log
2025/02/24 02:28 13m retest repro android13-5.10-lts report log
2025/02/24 02:28 7m retest repro android13-5.10-lts report log
2025/02/24 02:28 11m retest repro android13-5.10-lts report log
2025/02/24 02:28 5m retest repro android13-5.10-lts report log
2025/01/16 13:54 48m retest repro android13-5.10-lts report log
2025/01/04 17:56 45m retest repro android13-5.10-lts report log
2024/12/07 21:49 14m retest repro android13-5.10-lts report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbea/0xe30 fs/ext4/extents.c:945
Read of size 4 at addr ffff888120191650 by task kworker/u4:2/49

CPU: 1 PID: 49 Comm: kworker/u4:2 Not tainted 5.10.236-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
 ext4_find_extent+0xbea/0xe30 fs/ext4/extents.c:945
 ext4_ext_map_blocks+0x26a/0x6ee0 fs/ext4/extents.c:4159
 ext4_map_blocks+0xa65/0x1d10 fs/ext4/inode.c:673
 mpage_map_one_extent fs/ext4/inode.c:2451 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
 ext4_writepages+0x148b/0x3c00 fs/ext4/inode.c:2872
 do_writepages+0x12e/0x270 mm/page-writeback.c:2380
 __writeback_single_inode+0xd7/0xac0 fs/fs-writeback.c:1470
 writeback_sb_inodes+0x99c/0x16b0 fs/fs-writeback.c:1733
 wb_writeback+0x404/0xc60 fs/fs-writeback.c:1908
 wb_do_writeback fs/fs-writeback.c:2053 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2094
 process_one_work+0x6dc/0xbd0 kernel/workqueue.c:2301
 worker_thread+0xaea/0x1510 kernel/workqueue.c:2447
 kthread+0x34b/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the page:
page:ffffea0004806440 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x120191
flags: 0x4000000000000000()
raw: 4000000000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x8100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|0x8000000), pid 289, ts 35408351019, free_ts 35439338476
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x166/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2d8c/0x2f30 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x435/0xaf0 mm/page_alloc.c:5349
 __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]
 do_anonymous_page mm/memory.c:3963 [inline]
 handle_pte_fault+0x175a/0x3e10 mm/memory.c:4786
 __handle_mm_fault mm/memory.c:4944 [inline]
 handle_mm_fault+0x11d6/0x1a10 mm/memory.c:5358
 do_user_addr_fault arch/x86/mm/fault.c:1362 [inline]
 handle_page_fault arch/x86/mm/fault.c:1428 [inline]
 exc_page_fault+0x2a6/0x5b0 arch/x86/mm/fault.c:1484
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:571
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+0x2ae/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x122/0xb20 mm/page_alloc.c:3443
 release_pages+0xea0/0xef0 mm/swap.c:1103
 free_pages_and_swap_cache+0x8a/0xa0 mm/swap_state.c:356
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x177/0x320 mm/mmu_gather.c:326
 unmap_region+0x31c/0x370 mm/mmap.c:2799
 __do_munmap+0x699/0x8c0 mm/mmap.c:3029
 __vm_munmap mm/mmap.c:3082 [inline]
 __do_sys_munmap mm/mmap.c:3108 [inline]
 __se_sys_munmap+0x120/0x1a0 mm/mmap.c:3104
 __x64_sys_munmap+0x5b/0x70 mm/mmap.c:3104
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff888120191500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888120191580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888120191600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff888120191680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888120191700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2463!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 49 Comm: kworker/u4:2 Tainted: G    B             5.10.236-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2463 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
RIP: 0010:ext4_writepages+0x3b44/0x3c00 fs/ext4/inode.c:2872
Code: 00 74 08 48 89 df e8 fb fd c9 ff 48 8b 3b 48 8b 74 24 28 48 8b 54 24 50 44 89 e1 45 89 f8 e8 93 de 07 00 eb 5d e8 6c 5f 8c ff <0f> 0b e8 65 5f 8c ff eb 3b e8 5e 5f 8c ff eb 77 e8 57 5f 8c ff 31
RSP: 0018:ffffc900009e70a0 EFLAGS: 00010293
RAX: ffffffff81de6084 RBX: dffffc0000000000 RCX: ffff888101ffa780
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009e7490 R08: ffffffff81de3c89 R09: ffffed1021ffc25b
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc900009e73b0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe57dfe8748 CR3: 000000000660f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 do_writepages+0x12e/0x270 mm/page-writeback.c:2380
 __writeback_single_inode+0xd7/0xac0 fs/fs-writeback.c:1470
 writeback_sb_inodes+0x99c/0x16b0 fs/fs-writeback.c:1733
 wb_writeback+0x404/0xc60 fs/fs-writeback.c:1908
 wb_do_writeback fs/fs-writeback.c:2053 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2094
 process_one_work+0x6dc/0xbd0 kernel/workqueue.c:2301
 worker_thread+0xaea/0x1510 kernel/workqueue.c:2447
 kthread+0x34b/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace 636f3b377ee5b0cc ]---
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2463 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2504 [inline]
RIP: 0010:ext4_writepages+0x3b44/0x3c00 fs/ext4/inode.c:2872
Code: 00 74 08 48 89 df e8 fb fd c9 ff 48 8b 3b 48 8b 74 24 28 48 8b 54 24 50 44 89 e1 45 89 f8 e8 93 de 07 00 eb 5d e8 6c 5f 8c ff <0f> 0b e8 65 5f 8c ff eb 3b e8 5e 5f 8c ff eb 77 e8 57 5f 8c ff 31
RSP: 0018:ffffc900009e70a0 EFLAGS: 00010293
RAX: ffffffff81de6084 RBX: dffffc0000000000 RCX: ffff888101ffa780
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009e7490 R08: ffffffff81de3c89 R09: ffffed1021ffc25b
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc900009e73b0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe57dfe8748 CR3: 000000000660f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (31):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/18 21:12 android13-5.10-lts ba8b8b193394 2a20f901 .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_find_extent
2025/02/10 01:47 android13-5.10-lts 6686f2996d23 ef44b750 .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_find_extent
2023/04/01 05:47 android12-5.10-lts 416c4356f372 f325deb0 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/19 01:42 android12-5.10-lts 416c4356f372 7939252e .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2025/03/15 07:32 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 Read in ext4_find_extent
2022/12/21 09:05 android12-5.10-lts 003c389455eb d3e76707 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2022/12/12 16:05 android12-5.10-lts f3226d86f8ce 67be1ae7 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2022/12/04 17:23 android12-5.10-lts 25af5a11f1da e080de16 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2022/12/26 07:48 android12-5.10-lts 003c389455eb 9da18ae8 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2025/04/28 05:45 android13-5.10-lts ba8b8b193394 c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2025/03/25 20:48 android13-5.10-lts 094fc3778d6b 875573af .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2025/02/10 01:03 android13-5.10-lts 6686f2996d23 ef44b750 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2024/11/23 21:22 android13-5.10-lts b14940b90491 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2024/10/08 01:40 android13-5.10-lts e5e5644ea27f d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2024/10/05 09:57 android13-5.10-lts e5e5644ea27f d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2024/09/02 16:32 android13-5.10-lts 1c5354a314ea 1eda0d14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/09/10 01:17 android13-5.10-lts a27512601c2d 6654cf89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/09/09 20:25 android13-5.10-lts a27512601c2d 6654cf89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/06/12 10:23 android13-5.10-lts 43c801dc3325 49519f06 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/05/22 05:46 android13-5.10-lts 43c801dc3325 4bce1a3e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/04/26 09:25 android12-5.10-lts 416c4356f372 65320f8e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/04/06 18:08 android12-5.10-lts 416c4356f372 08707520 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/04/04 06:55 android12-5.10-lts 416c4356f372 41147e3e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/28 08:43 android12-5.10-lts 416c4356f372 47f3aaf1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/27 18:47 android12-5.10-lts 416c4356f372 f8f96aa9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/16 12:53 android12-5.10-lts 416c4356f372 18b58603 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/14 03:54 android12-5.10-lts 416c4356f372 026e2200 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/11 04:18 android12-5.10-lts 416c4356f372 5205ef30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/02/24 17:51 android12-5.10-lts 416c4356f372 ee50e71c .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2022/12/14 02:10 android12-5.10-lts 202ee063496e f6511626 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_find_extent
2023/03/03 01:51 android12-5.10-lts 416c4356f372 f8902b57 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_find_extent
* Struck through repros no longer work on HEAD.