KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache

Status: premoderation: reported on 2026/08/04 13:01
Reported-by: syzbot+bb423d71dd25405fd560@syzkaller.appspotmail.com
First crash: 6d10h, last: 21h15m
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache 19 1 4d23h 4d23h 0/2 premoderation: reported on 2026/08/06 00:17

Sample crash report:
netlink: 96 bytes leftover after parsing attributes in process `syz.0.1676'.
==================================================================
BUG: KASAN: use-after-free in trace_event_raw_event_mm_filemap_op_page_cache+0x3c6/0x3f0 include/trace/events/filemap.h:-1
Read of size 4 at addr ffff88811bb43010 by task syz.0.1676/6586

CPU: 0 PID: 6586 Comm: syz.0.1676 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x10f/0x150 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 trace_event_raw_event_mm_filemap_op_page_cache+0x3c6/0x3f0 include/trace/events/filemap.h:-1
 trace_mm_filemap_delete_from_page_cache include/trace/events/filemap.h:47 [inline]
 __delete_from_page_cache+0x418/0x470 mm/filemap.c:238
 __remove_mapping+0x601/0x990 mm/vmscan.c:1216
 shrink_page_list+0x2a24/0x5800 mm/vmscan.c:1829
 shrink_inactive_list mm/vmscan.c:2338 [inline]
 shrink_list mm/vmscan.c:2583 [inline]
 shrink_lruvec+0x1297/0x3a40 mm/vmscan.c:5800
 shrink_node_memcgs mm/vmscan.c:5992 [inline]
 shrink_node+0x11ee/0x2a40 mm/vmscan.c:6022
 shrink_zones mm/vmscan.c:6228 [inline]
 do_try_to_free_pages+0x5a7/0x1580 mm/vmscan.c:6286
 try_to_free_mem_cgroup_pages+0x261/0x610 mm/vmscan.c:6600
 mem_cgroup_resize_max+0x309/0x3e0 mm/memcontrol.c:3474
 mem_cgroup_write+0x1ed/0x230 mm/memcontrol.c:-1
 cgroup_file_write+0x294/0x560 kernel/cgroup/cgroup.c:4011
 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2212 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x831/0xfd0 fs/read_write.c:594
 ksys_write+0x14a/0x260 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 x64_sys_call+0x8ef/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9fb07220d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9faf17b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9fb09a9fa0 RCX: 00007f9fb07220d9
RDX: 000000000000011a RSI: 0000200000000340 RDI: 0000000000000004
RBP: 00007f9fb07b9024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9fb09aa038 R14: 00007f9fb09a9fa0 R15: 00007ffc4bc8e7e8
 </TASK>

Allocated by task 6318:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 ____kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521
 kasan_kmalloc include/linux/kasan.h:227 [inline]
 kmem_cache_alloc_trace+0x119/0x270 mm/slub.c:3274
 kmalloc include/linux/slab.h:619 [inline]
 kzalloc include/linux/slab.h:750 [inline]
 alloc_super+0x5e/0x840 fs/super.c:203
 sget+0x1e2/0x4c0 fs/super.c:637
 mount_bdev+0xec/0x3c0 fs/super.c:1373
 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4713
 legacy_get_tree+0xed/0x190 fs/fs_context.c:611
 vfs_get_tree+0x89/0x260 fs/super.c:1530
 do_new_mount+0x251/0xb40 fs/namespace.c:3037
 path_mount+0x640/0xff0 fs/namespace.c:3367
 do_mount fs/namespace.c:3380 [inline]
 __do_sys_mount fs/namespace.c:3588 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3565
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3565
 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 2521:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
 kasan_slab_free include/linux/kasan.h:193 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754
 slab_free mm/slub.c:3526 [inline]
 kfree+0xc4/0x270 mm/slub.c:4588
 destroy_super_work+0x40/0x50 fs/super.c:165
 process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328
 worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475
 kthread+0x3f5/0x4f0 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
 insert_work+0x51/0x310 kernel/workqueue.c:1373
 __queue_work+0x8e1/0xc60 kernel/workqueue.c:1539
 queue_work_on+0xde/0x150 kernel/workqueue.c:1566
 queue_work include/linux/workqueue.h:510 [inline]
 schedule_work include/linux/workqueue.h:571 [inline]
 destroy_super_rcu+0xd1/0xe0 fs/super.c:172
 rcu_do_batch+0x4c1/0xbf0 kernel/rcu/tree.c:2523
 rcu_core+0x4a3/0xef0 kernel/rcu/tree.c:2763
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2776
 handle_softirqs+0x250/0x560 kernel/softirq.c:583
 __do_softirq kernel/softirq.c:621 [inline]
 invoke_softirq kernel/softirq.c:443 [inline]
 __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:670
 irq_exit_rcu+0x9/0x10 kernel/softirq.c:682
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:676

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
 __call_rcu_common kernel/rcu/tree.c:3011 [inline]
 call_rcu+0x10b/0xf60 kernel/rcu/tree.c:3129
 __put_super+0x26b/0x2d0 fs/super.c:299
 put_super fs/super.c:313 [inline]
 deactivate_locked_super+0xd4/0x100 fs/super.c:346
 mount_bdev+0x2ab/0x3c0 fs/super.c:1402
 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4713
 legacy_get_tree+0xed/0x190 fs/fs_context.c:611
 vfs_get_tree+0x89/0x260 fs/super.c:1530
 do_new_mount+0x251/0xb40 fs/namespace.c:3037
 path_mount+0x640/0xff0 fs/namespace.c:3367
 do_mount fs/namespace.c:3380 [inline]
 __do_sys_mount fs/namespace.c:3588 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3565
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3565
 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88811bb43000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
 2048-byte region [ffff88811bb43000, ffff88811bb43800)
The buggy address belongs to the page:
page:ffffea00046ed000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11bb40
head:ffffea00046ed000 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 0000000100000001 ffff888100043200
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5711, ts 234738321879, free_ts 234335064868
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1937 [inline]
 new_slab+0xa0/0x4d0 mm/slub.c:2000
 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033
 __slab_alloc+0x49/0x90 mm/slub.c:3120
 slab_alloc_node mm/slub.c:3211 [inline]
 slab_alloc mm/slub.c:3255 [inline]
 __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4954
 kmalloc_reserve net/core/skbuff.c:357 [inline]
 pskb_expand_head+0x123/0x1280 net/core/skbuff.c:1734
 netlink_trim+0x193/0x230 net/netlink/af_netlink.c:1303
 netlink_broadcast_filtered+0x75/0x1280 net/netlink/af_netlink.c:1520
 netlink_broadcast net/netlink/af_netlink.c:1565 [inline]
 nlmsg_multicast include/net/netlink.h:1033 [inline]
 nlmsg_notify+0xe9/0x1a0 net/netlink/af_netlink.c:2559
 rtnl_notify net/core/rtnetlink.c:762 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:3912 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:3927 [inline]
 rtmsg_ifinfo+0xea/0x130 net/core/rtnetlink.c:3933
 __dev_notify_flags+0xe0/0x5b0 net/core/dev.c:8921
 rtnl_configure_link+0x221/0x340 net/core/rtnetlink.c:-1
 __rtnl_newlink net/core/rtnetlink.c:3536 [inline]
 rtnl_newlink+0x1502/0x1900 net/core/rtnetlink.c:3576
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1474 [inline]
 free_pcp_prepare mm/page_alloc.c:1546 [inline]
 free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536
 free_unref_page+0xae/0x540 mm/page_alloc.c:3618
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x6c/0x100 mm/page_alloc.c:5900
 __vunmap+0x801/0x980 mm/vmalloc.c:2660
 __vfree mm/vmalloc.c:2709 [inline]
 vfree+0x8b/0xc0 mm/vmalloc.c:2740
 kcov_put kernel/kcov.c:417 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:519
 __fput+0x22b/0x900 fs/file_table.c:311
 ____fput+0x15/0x20 fs/file_table.c:339
 task_work_run+0x127/0x190 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xb70/0x29a0 kernel/exit.c:890
 do_group_exit+0x149/0x310 kernel/exit.c:1004
 __do_sys_exit_group kernel/exit.c:1015 [inline]
 __se_sys_exit_group kernel/exit.c:1013 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1013
 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88811bb42f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88811bb42f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88811bb43000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88811bb43080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811bb43100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/10 02:14 android13-5.15-lts 6148a1b6bae4 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/06 08:07 android13-5.15-lts b885b84af7a2 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/05 15:23 android13-5.15-lts b885b84af7a2 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/05 14:52 android13-5.15-lts b885b84af7a2 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/04 13:00 android13-5.15-lts b885b84af7a2 9451e17e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
* Struck through repros no longer work on HEAD.