KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache

Status: premoderation: reported on 2026/08/06 00:17
Reported-by: syzbot+df0848ecb10a50bba795@syzkaller.appspotmail.com
First crash: 6d22h, last: 9h26m
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache 19 7 9h33m 8d09h 0/2 premoderation: reported on 2026/08/04 13:01

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in trace_event_raw_event_mm_filemap_op_page_cache+0x38a/0x3b0 include/trace/events/filemap.h:-1
Read of size 4 at addr ffff888123e4d010 by task syz.1.2360/9295

CPU: 0 PID: 9295 Comm: syz.1.2360 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 trace_event_raw_event_mm_filemap_op_page_cache+0x38a/0x3b0 include/trace/events/filemap.h:-1
 trace_mm_filemap_delete_from_page_cache include/trace/events/filemap.h:47 [inline]
 __delete_from_page_cache+0x429/0x470 mm/filemap.c:241
 __remove_mapping+0x581/0x6b0 mm/vmscan.c:985
 shrink_page_list+0x21ee/0x4160 mm/vmscan.c:1498
 shrink_inactive_list+0x90c/0xef0 mm/vmscan.c:2075
 shrink_list mm/vmscan.c:2294 [inline]
 shrink_lruvec+0x2806/0x2d70 mm/vmscan.c:5473
 shrink_node_memcgs mm/vmscan.c:5660 [inline]
 shrink_node+0xee0/0x2690 mm/vmscan.c:5690
 shrink_zones mm/vmscan.c:5896 [inline]
 do_try_to_free_pages+0x602/0x1590 mm/vmscan.c:5954
 try_to_free_mem_cgroup_pages+0x261/0x610 mm/vmscan.c:6272
 mem_cgroup_resize_max+0x309/0x3e0 mm/memcontrol.c:3383
 mem_cgroup_write+0x1ed/0x230 mm/memcontrol.c:-1
 cgroup_file_write+0x294/0x560 kernel/cgroup/cgroup.c:3902
 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2066 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fdf0734f0d9
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:00007fdf05da8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fdf075d6fa0 RCX: 00007fdf0734f0d9
RDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000005
RBP: 00007fdf073e6024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdf075d7038 R14: 00007fdf075d6fa0 R15: 00007ffd95e8fe98

Allocated by task 4906:
 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:430 [inline]
 ____kasan_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x19f/0x330 mm/slub.c:4038
 __kmalloc_node include/linux/slab.h:421 [inline]
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x88/0x130 mm/util.c:612
 kvmalloc include/linux/mm.h:833 [inline]
 kvmalloc_array include/linux/mm.h:851 [inline]
 alloc_fdtable+0xea/0x2a0 fs/file.c:150
 dup_fd+0x7a2/0xab0 fs/file.c:360
 copy_files+0xcf/0x170 kernel/fork.c:1541
 copy_process+0x12d6/0x3320 kernel/fork.c:2256
 kernel_clone+0x233/0x950 kernel/fork.c:2650
 __do_sys_clone kernel/fork.c:2776 [inline]
 __se_sys_clone kernel/fork.c:2760 [inline]
 __x64_sys_clone+0x198/0x210 kernel/fork.c:2760
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 9090:
 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:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kfree+0xc0/0x270 mm/slub.c:4196
 kvfree+0x35/0x40 mm/util.c:647
 __free_fdtable fs/file.c:36 [inline]
 put_files_struct+0x275/0x310 fs/file.c:463
 exit_files+0x80/0xa0 fs/file.c:488
 do_exit+0xa45/0x24e0 kernel/exit.c:868
 do_group_exit+0x149/0x310 kernel/exit.c:987
 get_signal+0xfb1/0x1300 kernel/signal.c:2794
 arch_do_signal_or_restart+0xe7/0x11b0 arch/x86/kernel/signal.c:805
 handle_signal_work kernel/entry/common.c:145 [inline]
 exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

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+0x51/0x320 kernel/workqueue.c:1352
 __queue_work+0x91f/0xca0 kernel/workqueue.c:1518
 queue_work_on+0xe6/0x140 kernel/workqueue.c:1545
 queue_work include/linux/workqueue.h:515 [inline]
 schedule_work include/linux/workqueue.h:576 [inline]
 destroy_super_rcu+0xd1/0xe0 fs/super.c:172
 rcu_do_batch+0x488/0xaf0 kernel/rcu/tree.c:2494
 rcu_core+0x50a/0xca0 kernel/rcu/tree.c:2735
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2748
 __do_softirq+0x255/0x563 kernel/softirq.c:309

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 kernel/rcu/tree.c:2980 [inline]
 call_rcu+0x11a/0x1090 kernel/rcu/tree.c:3054
 __put_super+0x254/0x2b0 fs/super.c:299
 put_super fs/super.c:313 [inline]
 deactivate_locked_super+0xd4/0x100 fs/super.c:346
 mount_bdev+0x288/0x380 fs/super.c:1444
 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4598
 legacy_get_tree+0xed/0x190 fs/fs_context.c:593
 vfs_get_tree+0x89/0x260 fs/super.c:1572
 do_new_mount+0x25a/0xa30 fs/namespace.c:3006
 path_mount+0x581/0xca0 fs/namespace.c:3336
 do_mount fs/namespace.c:3349 [inline]
 __do_sys_mount fs/namespace.c:3557 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3534
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3534
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888123e4d000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
 2048-byte region [ffff888123e4d000, ffff888123e4d800)
The buggy address belongs to the page:
page:ffffea00048f9200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x123e48
head:ffffea00048f9200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042d80
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 3328, ts 202402561483, free_ts 201221568578
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc_track_caller+0x1e4/0x310 mm/slub.c:4541
 __kmalloc_reserve net/core/skbuff.c:144 [inline]
 __alloc_skb+0xdc/0x520 net/core/skbuff.c:212
 alloc_skb include/linux/skbuff.h:1126 [inline]
 nlmsg_new include/net/netlink.h:953 [inline]
 audit_buffer_alloc kernel/audit.c:1803 [inline]
 audit_log_start+0x41b/0x840 kernel/audit.c:1921
 common_lsm_audit+0xd4/0x1850 security/lsm_audit.c:457
 slow_avc_audit+0x1c4/0x240 security/selinux/avc.c:798
 avc_audit security/selinux/include/avc.h:140 [inline]
 avc_has_perm+0x215/0x3d0 security/selinux/avc.c:1201
 inode_has_perm security/selinux/hooks.c:1663 [inline]
 file_path_has_perm security/selinux/hooks.c:1708 [inline]
 selinux_file_open+0x47c/0x640 security/selinux/hooks.c:3985
 security_file_open+0x62/0xa0 security/security.c:1582
 do_dentry_open+0x37f/0x10a0 fs/open.c:806
 vfs_open+0x73/0x80 fs/open.c:944
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+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page mm/page_alloc.c:5443 [inline]
 __free_pages+0x146/0x390 mm/page_alloc.c:5454
 __vunmap+0x801/0x980 mm/vmalloc.c:2307
 __vfree mm/vmalloc.c:2356 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2387
 kcov_mmap+0x8f/0x130 kernel/kcov.c:489
 call_mmap include/linux/fs.h:2071 [inline]
 mmap_file+0x60/0xb0 mm/util.c:1085
 __mmap_region mm/mmap.c:1884 [inline]
 mmap_region+0x11fd/0x19c0 mm/mmap.c:3075
 do_mmap+0x85f/0xf50 mm/mmap.c:1661
 vm_mmap_pgoff+0x1f4/0x350 mm/util.c:543
 ksys_mmap_pgoff+0x16f/0x1e0 mm/mmap.c:1712
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:95 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff888123e4cf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888123e4cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888123e4d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888123e4d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888123e4d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/12 13:13 android13-5.10-lts 8e2d2cc88387 f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/12 04:39 android13-5.10-lts dce28bf8c73c f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
2026/08/06 00:16 android13-5.10-lts 0f73d4924a74 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in trace_event_raw_event_mm_filemap_op_page_cache
* Struck through repros no longer work on HEAD.