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KASAN: use-after-free Read in ext4_find_extent (2)

Status: upstream: reported C repro on 2025/05/31 08:45
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+869401e856e234844286@syzkaller.appspotmail.com
First crash: 104d, last: 8d23h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/06/01 lts (merge base) 02b72ccb5f9d C [report] KASAN: use-after-free Read in ext4_find_extent
2025/06/01 upstream (ToT) cd2e103d57e5 C Didn't crash
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-54 KASAN: use-after-free Read in ext4_find_extent 19 C 2 112d 210d 0/2 upstream: reported C repro on 2025/02/13 21:05
android-5-10 KASAN: use-after-free Read in ext4_find_extent ext4 19 C error inconclusive 49 1h34m 991d 0/2 upstream: reported C repro on 2022/12/26 07:59
android-6-1 KASAN: use-after-free Read in ext4_find_extent missing-backport 19 C error done 3 320d 817d 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 19 C inconclusive 7 39d 785d 0/3 upstream: reported C repro on 2023/07/19 14:49
upstream KASAN: use-after-free Read in ext4_find_extent ext4 19 2 1423d 1484d 0/29 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 19 C done 60 13d 724d 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 19 C error 92 7d09h 991d 0/2 upstream: reported C repro on 2022/12/26 07:59
upstream KASAN: use-after-free Read in ext4_find_extent (2) ext4 19 C error 2 861d 986d 22/29 fixed on 2023/06/08 14:41
upstream KASAN: use-after-free Read in ext4_find_extent (4) ext4 19 C done 109 3d09h 255d 0/29 upstream: reported C repro on 2024/12/30 20:06
upstream KASAN: use-after-free Read in ext4_find_extent (3) prio:low ext4 19 C error done 31 626d 807d 25/29 fixed on 2024/01/30 23:26
android-54 KASAN: slab-out-of-bounds Read in ext4_find_extent ext4 17 C 1 805d 991d 0/2 auto-obsoleted due to no activity on 2023/10/08 03:20
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2025/08/23 21:20 12m retest repro android14-6.1 report log
2025/06/14 21:11 6m retest repro android14-6.1 report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/07/31 06:27 1h21m bisect fix android14-6.1 OK (0) job log log
2025/06/30 20:17 1h08m bisect fix android14-6.1 OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
Read of size 4 at addr ffff88812901c018 by task kworker/u4:1/10

CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x71/0x1e0 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:418
 kasan_report+0x122/0x150 mm/kasan/report.c:522
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
 ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
 ext4_ext_map_blocks+0x1dc/0x6060 fs/ext4/extents.c:4166

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/03 14:52 android14-6.1 79ccb6ecf51e 96a211bc .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/08/03 17:31 android14-6.1 3b4ff5af8d36 7368264b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/05/31 08:37 android14-6.1 db710ea87c32 3d2f584d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/08/28 01:48 android14-6.1 47b374a18638 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/08/28 01:48 android14-6.1 47b374a18638 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/08/28 01:46 android14-6.1 47b374a18638 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/08/28 01:46 android14-6.1 47b374a18638 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
2025/05/31 08:03 android14-6.1 db710ea87c32 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in ext4_find_extent
* Struck through repros no longer work on HEAD.