================================================================== BUG: KASAN: slab-use-after-free in netfs_unbuffered_write+0x1bde/0x21b0 fs/netfs/direct_write.c:119 Read of size 2 at addr ffff88806b8f0e64 by task syz.9.4838/22701 CPU: 1 UID: 0 PID: 22701 Comm: syz.9.4838 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/0x1c0 mm/kasan/report.c:595 netfs_unbuffered_write+0x1bde/0x21b0 fs/netfs/direct_write.c:119 netfs_unbuffered_write_iter_locked+0x7cd/0xa80 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x720 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/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf6feefec Code: Unable to access opcode bytes at 0xf6feefc2. RSP: 002b:00000000f4f7850c EFLAGS: 00000292 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000080000300 RDX: 000000000000fdef RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 22701: 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:4612 [inline] slab_alloc_node mm/slub.c:4945 [inline] kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4959 mempool_alloc_noprof+0x1b7/0x310 mm/mempool.c:559 netfs_alloc_subrequest+0xc1/0x3c0 fs/netfs/objects.c:204 netfs_prepare_write+0x76/0x780 fs/netfs/write_issue.c:172 netfs_unbuffered_write+0x7ba/0x21b0 fs/netfs/direct_write.c:111 netfs_unbuffered_write_iter_locked+0x7cd/0xa80 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x720 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/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e Freed by task 22701: 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:2705 [inline] slab_free mm/slub.c:6405 [inline] kmem_cache_free+0x127/0x6b0 mm/slub.c:6532 mempool_free+0xde/0x130 mm/mempool.c:704 netfs_free_subrequest fs/netfs/objects.c:239 [inline] netfs_put_subrequest+0x282/0x4b0 fs/netfs/objects.c:255 netfs_unbuffered_write+0x13c0/0x21b0 fs/netfs/direct_write.c:118 netfs_unbuffered_write_iter_locked+0x7cd/0xa80 fs/netfs/direct_write.c:294 netfs_unbuffered_write_iter+0x442/0x720 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/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e The buggy address belongs to the object at ffff88806b8f0dc0 which belongs to the cache netfs_subrequest of size 200 The buggy address is located 164 bytes inside of freed 200-byte region [ffff88806b8f0dc0, ffff88806b8f0e88) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806b8f17c0 pfn:0x6b8f0 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88806b8f00d9 flags: 0x4fff00000000240(workingset|head|node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000240 ffff888021272dc0 ffffea00014dd290 ffff88804228de88 raw: ffff88806b8f17c0 000001400019000c 00000000f5000000 ffff88806b8f00d9 head: 04fff00000000240 ffff888021272dc0 ffffea00014dd290 ffff88804228de88 head: ffff88806b8f17c0 000001400019000c 00000000f5000000 ffff88806b8f00d9 head: 04fff00000000001 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 0xd2800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 18072, tgid 18065 (syz.8.3465), ts 757578583271, free_ts 757443989594 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304 alloc_slab_page mm/slub.c:3294 [inline] allocate_slab mm/slub.c:3408 [inline] new_slab+0xa2/0x650 mm/slub.c:3454 refill_objects+0xe3/0x410 mm/slub.c:7338 refill_sheaf mm/slub.c:2832 [inline] __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4703 alloc_from_pcs mm/slub.c:4801 [inline] slab_alloc_node mm/slub.c:4933 [inline] kmem_cache_alloc_noprof+0x46e/0x6a0 mm/slub.c:4959 mempool_alloc_noprof+0x1b7/0x310 mm/mempool.c:559 netfs_alloc_subrequest+0xc1/0x3c0 fs/netfs/objects.c:204 netfs_read_to_pagecache+0x22a/0x9b0 fs/netfs/buffered_read.c:221 netfs_readahead+0x5c2/0x770 fs/netfs/buffered_read.c:364 read_pages+0x1b1/0xdf0 mm/readahead.c:174 page_cache_ra_unbounded+0x48a/0x990 mm/readahead.c:315 do_page_cache_ra+0x10f/0x160 mm/readahead.c:348 page_cache_ra_order+0xc05/0xed0 mm/readahead.c:558 page_cache_async_ra+0x7bb/0xd30 mm/readahead.c:720 page last free pid 5753 tgid 5753 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4612 [inline] slab_alloc_node mm/slub.c:4945 [inline] kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4959 locks_alloc_lock fs/locks.c:285 [inline] flock_lock_inode+0xccd/0x11a0 fs/locks.c:1150 flock_lock_inode_wait fs/locks.c:2229 [inline] locks_lock_inode_wait+0x119/0x490 fs/locks.c:2256 locks_lock_file_wait include/linux/filelock.h:461 [inline] __do_sys_flock+0x462/0x4d0 fs/locks.c:2324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88806b8f0d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b8f0d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff88806b8f0e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88806b8f0e80: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88806b8f0f00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================