Sysenter RSP=0000000000000000 CS:RIP=0000:0000000000000000 CS: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 DS: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 ================================================================== BUG: KASAN: use-after-free in p9_client_clunk+0x1fc/0x240 net/9p/client.c:1505 SS: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 Read of size 8 at addr ffff8880a36fa700 by task syz-executor.4/20301 CPU: 0 PID: 20301 Comm: syz-executor.4 Not tainted 4.14.232-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252 ES: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351 kasan_report mm/kasan/report.c:409 [inline] __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430 p9_client_clunk+0x1fc/0x240 net/9p/client.c:1505 v9fs_mount+0x69f/0x860 fs/9p/vfs_super.c:200 mount_fs+0x92/0x2a0 fs/super.c:1237 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0xe53/0x2a00 fs/namespace.c:2879 FS: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 GS: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xa8/0x120 fs/namespace.c:3072 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 GDTR: limit=0x00000000, base=0x0000000000000000 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4665d9 RSP: 002b:00007f52adb25188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665d9 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 00007f52adb251d0 R08: 0000000020000180 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007fffbecc4def R14: 00007f52adb25300 R15: 0000000000022000 Allocated by task 20301: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] p9_fid_create+0x47/0x3a0 net/9p/client.c:918 LDTR: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 p9_client_attach+0x6d/0x750 net/9p/client.c:1158 v9fs_session_init+0xc03/0x1540 fs/9p/v9fs.c:471 v9fs_mount+0x73/0x860 fs/9p/vfs_super.c:135 mount_fs+0x92/0x2a0 fs/super.c:1237 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0xe53/0x2a00 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xa8/0x120 fs/namespace.c:3072 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 20301: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xc9/0x250 mm/slab.c:3815 p9_client_destroy.cold+0x67/0xaa net/9p/client.c:1121 v9fs_session_close+0x45/0x2c0 fs/9p/v9fs.c:511 v9fs_kill_super+0x49/0x90 fs/9p/vfs_super.c:233 deactivate_locked_super+0x6c/0xd0 fs/super.c:319 sget_userns+0x9c4/0xc10 fs/super.c:537 IDTR: limit=0x00000000, base=0x0000000000000000 sget+0xd1/0x110 fs/super.c:572 v9fs_mount+0x9e/0x860 fs/9p/vfs_super.c:141 mount_fs+0x92/0x2a0 fs/super.c:1237 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0xe53/0x2a00 fs/namespace.c:2879 TR: sel=0x0000, attr=0x10000, limit=0x00000000, base=0x0000000000000000 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xa8/0x120 fs/namespace.c:3072 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8880a36fa700 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of 96-byte region [ffff8880a36fa700, ffff8880a36fa760) The buggy address belongs to the page: page:ffffea00028dbe80 count:1 mapcount:0 mapping:ffff8880a36fa000 index:0xffff8880a36fab80 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffff8880a36fa000 ffff8880a36fab80 000000010000001c raw: ffffea0002c712a0 ffffea00029433a0 ffff88813fe804c0 0000000000000000 EFER = 0x0000000000000000 PAT = 0x0007040600070406 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a36fa600: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc ffff8880a36fa680: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc >ffff8880a36fa700: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff8880a36fa780: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc ffff8880a36fa800: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ================================================================== audit: type=1804 audit(1621173935.719:7): pid=20321 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="ToMToU" comm="syz-executor.3" name="/root/syzkaller-testdir392613187/syzkaller.m1V2nP/306/file0" dev="sda1" ino=15011 res=1 DebugCtl = 0x0000000000000000 DebugExceptions = 0x0000000000000000 audit: type=1804 audit(1621173935.799:8): pid=20317 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="ToMToU" comm="syz-executor.3" name="/root/syzkaller-testdir392613187/syzkaller.m1V2nP/306/file0" dev="sda1" ino=15011 res=1 Interruptibility = 00000000 ActivityState = 00000000 audit: type=1804 audit(1621173935.799:9): pid=20321 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="ToMToU" comm="syz-executor.3" name="/root/syzkaller-testdir392613187/syzkaller.m1V2nP/306/file0" dev="sda1" ino=15011 res=1 *** Host State *** RIP = 0xffffffff811601fe RSP = 0xffff88804efef9b8 CS=0010 SS=0018 DS=0000 ES=0000 FS=0000 GS=0000 TR=0040 FSBase=00007fe71e400700 GSBase=ffff8880ba500000 TRBase=fffffe0000034000 GDTBase=fffffe0000032000 IDTBase=fffffe0000000000 CR0=0000000080050033 CR3=00000000a13d2000 CR4=00000000001426e0 Sysenter RSP=fffffe0000034000 CS:RIP=0010:ffffffff87401690 EFER = 0x0000000000000d01 PAT = 0x0407050600070106 *** Control State *** PinBased=0000003f CPUBased=b6986dfa SecondaryExec=000000e2 EntryControls=0000d1ff ExitControls=002fefff ExceptionBitmap=00060042 PFECmask=00000000 PFECmatch=00000000 VMEntry: intr_info=00000000 errcode=00000000 ilen=00000000