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006d021491bc7-69e1043fe9bmr2990219eaf.58.1780200242582; Sat, 30 May 2026 21:04:02 -0700 (PDT) Date: Sat, 30 May 2026 21:04:02 -0700 In-Reply-To: X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a1bb332.fd5edf16.2e7427.0009.GAE@google.com> Subject: Re: [syzbot] [netfs?] KASAN: slab-use-after-free Read in netfs_unbuffered_write From: syzbot To: eadavis@qq.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KASAN: slab-use-after-free Read in netfs_clear_subrequests ================================================================== BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x18a/0x1d0 lib/list_debug.c:49 Read of size 8 at addr ffff888028092f58 by task syz.0.17/6267 CPU: 3 UID: 0 PID: 6267 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 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 __list_del_entry_valid_or_report+0x18a/0x1d0 lib/list_debug.c:49 __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_del include/linux/list.h:260 [inline] netfs_clear_subrequests+0x98/0x260 fs/netfs/objects.c:105 netfs_unbuffered_write_done fs/netfs/direct_write.c:59 [inline] netfs_unbuffered_write+0x1358/0x21a0 fs/netfs/direct_write.c:202 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: 0033:0x7fbdafd9ce59 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:00007fbdb0bf8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fbdb0015fa0 RCX: 00007fbdafd9ce59 RDX: 00000000fffffdd8 RSI: 0000200000000540 RDI: 0000000000000003 RBP: 00007fbdafe32d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbdb0016038 R14: 00007fbdb0015fa0 R15: 00007ffe0da23988 Allocated by task 6267: 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+0x7b8/0x21a0 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 6267: 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+0x1420/0x21a0 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 The buggy address belongs to the object at ffff888028092f00 which belongs to the cache netfs_subrequest of size 200 The buggy address is located 88 bytes inside of freed 200-byte region [ffff888028092f00, ffff888028092fc8) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880280932c0 pfn:0x28092 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff8880280920d9 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff88801fad1680 ffff888022be5408 ffff888022be5408 raw: ffff8880280932c0 000001400019000f 00000000f5000000 ffff8880280920d9 head: 00fff00000000240 ffff88801fad1680 ffff888022be5408 ffff888022be5408 head: ffff8880280932c0 000001400019000f 00000000f5000000 ffff8880280920d9 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 6267, tgid 6266 (syz.0.17), ts 103792298291, free_ts 103737337363 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_unbuffered_write+0x7b8/0x21a0 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 page last free pid 6266 tgid 6266 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 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:4570 [inline] slab_alloc_node mm/slub.c:4899 [inline] __do_kmalloc_node mm/slub.c:5295 [inline] __kmalloc_noprof+0x2b9/0x850 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 [inline] tomoyo_realpath_from_path+0xb6/0x690 security/tomoyo/realpath.c:251 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_check_open_permission+0x2af/0x3c0 security/tomoyo/file.c:776 tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334 security_file_open+0xb5/0x1e0 security/security.c:2739 do_dentry_open+0x588/0x14d0 fs/open.c:924 vfs_open+0x82/0x3f0 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 Memory state around the buggy address: ffff888028092e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888028092e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888028092f00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888028092f80: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc ffff888028093000: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ================================================================== Tested on: commit: 174914ea Merge tag 'v7.1-rc6-smb3-client-fixes' of git.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13f0c27a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8118209836970b54 dashboard link: https://syzkaller.appspot.com/bug?extid=3c74b1f0c372e98efc32 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 patch: https://syzkaller.appspot.com/x/patch.diff?x=153097a6580000