================================================================== BUG: KFENCE: use-after-free read in kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline] BUG: KFENCE: use-after-free read in __kernfs_remove+0x283/0xb50 fs/kernfs/dir.c:1369 Use-after-free read at 0xffff88823bc5a098 (in kfence-#44): kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline] __kernfs_remove+0x283/0xb50 fs/kernfs/dir.c:1369 kernfs_remove_by_name_ns+0xa8/0x110 fs/kernfs/dir.c:1589 sysfs_slab_add+0x13e/0x1e0 mm/slub.c:5756 __kmem_cache_create+0x509/0x690 mm/slub.c:4745 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x1f9/0x300 mm/slab_common.c:335 p9_client_create+0xca5/0x1070 net/9p/client.c:993 v9fs_session_init+0x1e2/0x1810 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xc90 fs/9p/vfs_super.c:126 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd kfence-#44: 0xffff88823bc5a000-0xffff88823bc5a0a7, size=168, cache=kernfs_node_cache allocated by task 1804 on cpu 0 at 1453.141792s: kmem_cache_zalloc include/linux/slab.h:685 [inline] __kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:593 kernfs_new_node fs/kernfs/dir.c:655 [inline] kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:1010 sysfs_create_dir_ns+0x127/0x290 fs/sysfs/dir.c:59 create_dir lib/kobject.c:63 [inline] kobject_add_internal+0x2c9/0x8f0 lib/kobject.c:223 kobject_add_varg lib/kobject.c:358 [inline] kobject_init_and_add+0x101/0x160 lib/kobject.c:441 sysfs_slab_add+0x161/0x1e0 mm/slub.c:5767 __kmem_cache_create+0x509/0x690 mm/slub.c:4745 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x1f9/0x300 mm/slab_common.c:335 p9_client_create+0xca5/0x1070 net/9p/client.c:993 v9fs_session_init+0x1e2/0x1810 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xc90 fs/9p/vfs_super.c:126 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd freed by task 1809 on cpu 1 at 1453.723528s: kernfs_put.part.0+0x2c4/0x540 fs/kernfs/dir.c:547 kernfs_put+0x42/0x50 fs/kernfs/dir.c:521 __kernfs_remove+0x7a6/0xb50 fs/kernfs/dir.c:1407 kernfs_remove_by_name_ns+0xa8/0x110 fs/kernfs/dir.c:1589 sysfs_slab_add+0x13e/0x1e0 mm/slub.c:5756 __kmem_cache_create+0x509/0x690 mm/slub.c:4745 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x1f9/0x300 mm/slab_common.c:335 p9_client_create+0xca5/0x1070 net/9p/client.c:993 v9fs_session_init+0x1e2/0x1810 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xc90 fs/9p/vfs_super.c:126 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd CPU: 1 PID: 1809 Comm: syz-executor.4 Not tainted 6.0.0-rc2-next-20220825-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 RIP: 0010:kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline] RIP: 0010:__kernfs_remove+0x283/0xb50 fs/kernfs/dir.c:1369 Code: fe ff ff e8 3f 0b 7e ff 48 8b 85 00 ff ff ff 0f b6 00 84 c0 74 08 3c 01 0f 8e 86 07 00 00 4c 8b bd 28 ff ff ff bf 01 00 00 00 <41> 0f b7 87 98 00 00 00 89 c3 66 89 85 20 ff ff ff 83 e3 0f 89 de RSP: 0018:ffffc90005047770 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888051fede80 RCX: ffffc9000c881000 RDX: 0000000000040000 RSI: ffffffff81fdfec1 RDI: 0000000000000001 RBP: ffffc900050478a0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88823bc5a000 R13: ffff888051fedec0 R14: dffffc0000000000 R15: ffff88823bc5a000 FS: 00007fc2967af700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88823bc5a098 CR3: 00000000178ee000 CR4: 00000000003506e0 Call Trace: kernfs_remove_by_name_ns+0xa8/0x110 fs/kernfs/dir.c:1589 sysfs_slab_add+0x13e/0x1e0 mm/slub.c:5756 __kmem_cache_create+0x509/0x690 mm/slub.c:4745 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x1f9/0x300 mm/slab_common.c:335 p9_client_create+0xca5/0x1070 net/9p/client.c:993 v9fs_session_init+0x1e2/0x1810 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xc90 fs/9p/vfs_super.c:126 legacy_get_tree+0x105/0x220 fs/fs_context.c:610 vfs_get_tree+0x89/0x2f0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x1326/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fc295689279 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc2967af168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007fc29579bf80 RCX: 00007fc295689279 RDX: 0000000020000080 RSI: 00000000200002c0 RDI: 0000000000000000 RBP: 00007fc2956e3189 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd174c5c5f R14: 00007fc2967af300 R15: 0000000000022000 ================================================================== ---------------- Code disassembly (best guess), 3 bytes skipped: 0: e8 3f 0b 7e ff callq 0xff7e0b44 5: 48 8b 85 00 ff ff ff mov -0x100(%rbp),%rax c: 0f b6 00 movzbl (%rax),%eax f: 84 c0 test %al,%al 11: 74 08 je 0x1b 13: 3c 01 cmp $0x1,%al 15: 0f 8e 86 07 00 00 jle 0x7a1 1b: 4c 8b bd 28 ff ff ff mov -0xd8(%rbp),%r15 22: bf 01 00 00 00 mov $0x1,%edi * 27: 41 0f b7 87 98 00 00 movzwl 0x98(%r15),%eax <-- trapping instruction 2e: 00 2f: 89 c3 mov %eax,%ebx 31: 66 89 85 20 ff ff ff mov %ax,-0xe0(%rbp) 38: 83 e3 0f and $0xf,%ebx 3b: 89 de mov %ebx,%esi