================================================================== BUG: KASAN: slab-use-after-free in netfs_unbuffered_write+0x1c21/0x21e0 fs/netfs/direct_write.c:119 Read of size 2 at addr ffff88803f281724 by task syz.6.6556/26164 CPU: 3 UID: 0 PID: 26164 Comm: syz.6.6556 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1d0 mm/kasan/report.c:595 netfs_unbuffered_write+0x1c21/0x21e0 fs/netfs/direct_write.c:119 netfs_unbuffered_write_iter_locked+0x7e2/0xa90 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x740 fs/netfs/direct_write.c:386 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f874959ce59 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:00007f87477f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f8749815fa0 RCX: 00007f874959ce59 RDX: 00000000fffffdd8 RSI: 0000200000000540 RDI: 0000000000000004 RBP: 00007f8749632d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8749816038 R14: 00007f8749815fa0 R15: 00007ffdffcbb0b8 Allocated by task 26164: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4570 [inline] slab_alloc_node mm/slub.c:4899 [inline] kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4906 mempool_alloc_noprof+0x1b7/0x310 mm/mempool.c:566 netfs_alloc_subrequest+0xc1/0x3c0 fs/netfs/objects.c:204 netfs_prepare_write+0x76/0x780 fs/netfs/write_issue.c:172 netfs_unbuffered_write+0x7b8/0x21e0 fs/netfs/direct_write.c:111 netfs_unbuffered_write_iter_locked+0x7e2/0xa90 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x740 fs/netfs/direct_write.c:386 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 26164: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kmem_cache_free+0x127/0x6c0 mm/slub.c:6378 mempool_free+0xde/0x130 mm/mempool.c:711 netfs_free_subrequest fs/netfs/objects.c:239 [inline] netfs_put_subrequest+0x282/0x4c0 fs/netfs/objects.c:255 netfs_unbuffered_write+0x13ed/0x21e0 fs/netfs/direct_write.c:118 netfs_unbuffered_write_iter_locked+0x7e2/0xa90 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x740 fs/netfs/direct_write.c:386 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88803f281680 which belongs to the cache netfs_subrequest of size 200 The buggy address is located 164 bytes inside of freed 200-byte region [ffff88803f281680, ffff88803f281748) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803f281a40 pfn:0x3f280 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88803f2800d9 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff88801c3597c0 ffffea0001758190 ffffea0000b22c90 raw: ffff88803f281a40 0000014000190016 00000000f5000000 ffff88803f2800d9 head: 00fff00000000240 ffff88801c3597c0 ffffea0001758190 ffffea0000b22c90 head: ffff88803f281a40 0000014000190016 00000000f5000000 ffff88803f2800d9 head: 00fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2880(GFP_NOWAIT|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 24581, tgid 24581 (syz.5.6076), ts 595580790336, free_ts 587741119347 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1853 prep_new_page mm/page_alloc.c:1861 [inline] get_page_from_freelist+0x11a6/0x3410 mm/page_alloc.c:3941 __alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5221 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab mm/slub.c:3467 [inline] new_slab+0xa6/0x6c0 mm/slub.c:3525 refill_objects+0x277/0x420 mm/slub.c:7272 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x375/0x650 mm/slub.c:4652 alloc_from_pcs mm/slub.c:4750 [inline] slab_alloc_node mm/slub.c:4884 [inline] kmem_cache_alloc_noprof+0x480/0x6e0 mm/slub.c:4906 mempool_alloc_noprof+0x1b7/0x310 mm/mempool.c:566 netfs_alloc_subrequest+0xc1/0x3c0 fs/netfs/objects.c:204 netfs_prepare_write+0x76/0x780 fs/netfs/write_issue.c:172 netfs_advance_write fs/netfs/write_issue.c:298 [inline] netfs_advance_write+0x3af/0x4c0 fs/netfs/write_issue.c:278 netfs_write_folio+0xc09/0x1810 fs/netfs/write_issue.c:493 netfs_writepages+0x2b9/0x990 fs/netfs/write_issue.c:590 do_writepages+0x278/0x600 mm/page-writeback.c:2571 filemap_writeback+0x22d/0x2e0 mm/filemap.c:388 v9fs_dir_release+0x2d1/0x590 fs/9p/vfs_dir.c:219 page last free pid 50 tgid 50 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0x794/0x10a0 mm/page_alloc.c:2938 kasan_depopulate_vmalloc_pte+0x5d/0x80 mm/kasan/shadow.c:484 apply_to_pte_range mm/memory.c:3338 [inline] apply_to_pmd_range mm/memory.c:3382 [inline] apply_to_pud_range mm/memory.c:3418 [inline] apply_to_p4d_range mm/memory.c:3454 [inline] __apply_to_page_range+0xb1d/0x1520 mm/memory.c:3490 __kasan_release_vmalloc+0xd7/0xe0 mm/kasan/shadow.c:602 kasan_release_vmalloc include/linux/kasan.h:593 [inline] kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline] purge_vmap_node+0x210/0xb40 mm/vmalloc.c:2306 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff88803f281600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88803f281680: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88803f281700: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc ^ ffff88803f281780: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff88803f281800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================