KASAN: use-after-free Read in release_metapage (6)

Status: upstream: reported C repro on 2026/06/14 02:56
Reported-by: syzbot+0437695a987b689f5fde@syzkaller.appspotmail.com
First crash: 59d, last: 29d
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/08/07 upstream (ToT) 3f008280327b C Failed due to an error; will retry later
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in release_metapage (2) 19 3 568d 638d 0/3 auto-obsoleted due to no activity on 2025/05/01 23:31
linux-6.1 KASAN: use-after-free Read in release_metapage (5) 19 2 199d 200d 0/3 auto-obsoleted due to no activity on 2026/05/05 00:34
upstream KASAN: use-after-free Read in release_metapage jfs 19 syz, C error done 3324 3h52m 1318d 0/29 upstream: reported C repro on 2023/01/02 10:00
linux-6.1 KASAN: use-after-free Read in release_metapage 19 1 1057d 1057d 0/3 auto-obsoleted due to no activity on 2023/12/29 12:55
linux-5.15 BUG: spinlock bad magic in release_metapage origin:upstream 19 syz, C error 95 18d 696d 0/3 upstream: reported C repro on 2024/09/15 11:43
linux-4.14 KASAN: use-after-free Read in release_metapage 19 1 1372d 1372d 0/1 auto-obsoleted due to no activity on 2023/03/09 00:53
linux-6.1 KASAN: use-after-free Read in release_metapage (2) 19 1 832d 832d 0/3 auto-obsoleted due to no activity on 2024/08/10 05:44
linux-6.1 KASAN: use-after-free Read in release_metapage (4) 19 1 447d 447d 0/3 auto-obsoleted due to no activity on 2025/08/30 02:20
linux-5.15 KASAN: use-after-free Read in release_metapage 19 1 1035d 1035d 0/3 auto-obsoleted due to no activity on 2024/01/20 09:39
linux-6.1 KASAN: use-after-free Read in release_metapage (3) 19 1 638d 638d 0/3 auto-obsoleted due to no activity on 2025/02/20 12:24
upstream BUG: spinlock bad magic in release_metapage prio:high jfs 15 syz, C inconclusive 868 1d22h 701d 0/29 upstream: reported C repro on 2024/09/10 08:16
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/07/14 15:19 3h32m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
ERROR: (device loop2): remounting filesystem as read-only
==================================================================
BUG: KASAN: use-after-free in drop_metapage fs/jfs/jfs_metapage.c:223 [inline]
BUG: KASAN: use-after-free in release_metapage+0x718/0xc6c fs/jfs/jfs_metapage.c:757
Read of size 8 at addr ffff0000eb1a8500 by task syz.2.110/4630

CPU: 1 PID: 4630 Comm: syz.2.110 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 drop_metapage fs/jfs/jfs_metapage.c:223 [inline]
 release_metapage+0x718/0xc6c fs/jfs/jfs_metapage.c:757
 write_metapage fs/jfs/jfs_metapage.h:75 [inline]
 flush_metapage fs/jfs/jfs_metapage.h:81 [inline]
 ea_put fs/jfs/xattr.c:623 [inline]
 __jfs_setxattr+0xc14/0xfb8 fs/jfs/xattr.c:792
 __jfs_xattr_set+0xe0/0x178 fs/jfs/xattr.c:941
 jfs_xattr_set+0x58/0x70 fs/jfs/xattr.c:965
 __vfs_setxattr+0x384/0x3a0 fs/xattr.c:182
 __vfs_setxattr_noperm+0x120/0x564 fs/xattr.c:216
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:277
 vfs_setxattr+0x158/0x2ac fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x258/0x2d8 fs/xattr.c:617
 path_setxattr+0x130/0x260 fs/xattr.c:636
 __do_sys_lsetxattr fs/xattr.c:659 [inline]
 __se_sys_lsetxattr fs/xattr.c:655 [inline]
 __arm64_sys_lsetxattr+0xbc/0xd8 fs/xattr.c:655
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Allocated by task 4630:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x70/0x88 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x74/0x430 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x22c/0x308 mm/slub.c:3383
 mempool_alloc_slab+0x58/0x74 mm/mempool.c:532
 mempool_alloc+0x150/0x3fc mm/mempool.c:412
 alloc_metapage fs/jfs/jfs_metapage.c:176 [inline]
 __get_metapage+0x5c4/0xfac fs/jfs/jfs_metapage.c:651
 ea_get+0x874/0xed0 fs/jfs/xattr.c:528
 __jfs_setxattr+0x458/0xfb8 fs/jfs/xattr.c:727
 __jfs_xattr_set+0xe0/0x178 fs/jfs/xattr.c:941
 jfs_xattr_set+0x58/0x70 fs/jfs/xattr.c:965
 __vfs_setxattr+0x384/0x3a0 fs/xattr.c:182
 __vfs_setxattr_noperm+0x120/0x564 fs/xattr.c:216
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:277
 vfs_setxattr+0x158/0x2ac fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x258/0x2d8 fs/xattr.c:617
 path_setxattr+0x130/0x260 fs/xattr.c:636
 __do_sys_lsetxattr fs/xattr.c:659 [inline]
 __se_sys_lsetxattr fs/xattr.c:655 [inline]
 __arm64_sys_lsetxattr+0xbc/0xd8 fs/xattr.c:655
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Freed by task 4629:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0x118/0x314 mm/slub.c:3709
 mempool_free_slab+0x28/0x38 mm/mempool.c:539
 mempool_free+0xbc/0x2e0 mm/mempool.c:521
 free_metapage fs/jfs/jfs_metapage.c:191 [inline]
 metapage_release_folio+0x44c/0x5b4 fs/jfs/jfs_metapage.c:551
 filemap_release_folio+0x170/0x248 mm/filemap.c:4026
 mapping_evict_folio+0x1a8/0x264 mm/truncate.c:303
 invalidate_mapping_pagevec+0x2c0/0x50c mm/truncate.c:552
 invalidate_mapping_pages+0x38/0x4c mm/truncate.c:591
 drop_pagecache_sb+0x16c/0x220 fs/drop_caches.c:39
 iterate_supers+0x11c/0x1d0 fs/super.c:757
 drop_caches_sysctl_handler+0xb8/0x2fc fs/drop_caches.c:62
 proc_sys_call_handler+0x400/0x6a4 fs/proc/proc_sysctl.c:602
 proc_sys_write+0x2c/0x3c fs/proc/proc_sysctl.c:628
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x53c/0x940 fs/read_write.c:861
 vfs_iter_write+0x88/0xac fs/read_write.c:902
 iter_file_splice_write+0x520/0xa7c fs/splice.c:685
 do_splice_from fs/splice.c:763 [inline]
 direct_splice_actor+0xe4/0x134 fs/splice.c:950
 splice_direct_to_actor+0x3a0/0x954 fs/splice.c:896
 do_splice_direct+0x168/0x25c fs/splice.c:1002
 do_sendfile+0x478/0xcc8 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __arm64_sys_sendfile64+0x20c/0x36c fs/read_write.c:1309
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the object at ffff0000eb1a84d8
 which belongs to the cache jfs_mp of size 184
The buggy address is located 40 bytes inside of
 184-byte region [ffff0000eb1a84d8, ffff0000eb1a8590)

The buggy address belongs to the physical page:
page:0000000036a45ce9 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b1a8
flags: 0x5ffc00000000200(slab|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000200 0000000000000000 dead000000000001 ffff0000c71bcc00
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000eb1a8400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000eb1a8480: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb
>ffff0000eb1a8500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff0000eb1a8580: fb fb fc fc fc fc fc fc fc fc fb fb fb fb fb fb
 ffff0000eb1a8600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
syz.2.110 (4630): drop_caches: 1
syz.2.110 (4630): drop_caches: 1

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/14 08:02 linux-6.1.y 228da13e907e 1d2f3589 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in release_metapage
2026/06/14 02:55 linux-6.1.y 228da13e907e 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in release_metapage
* Struck through repros no longer work on HEAD.