CVE-2023-52751: In the Linux kernel, the following vulnerability has been resolved:  smb: client: fix use-after-free in smb2_query_info_compound()  The following UAF was triggered when running fstests generic/072 with KASAN enabled against Windows Server 2022 and mount options 'multichannel,max_channels=2,vers=3.1.1,mfsymlinks,noperm'    BUG: KASAN: slab-use-after-free in smb2_query_info_compound+0x423/0x6d0 [cifs]   Read of size 8 at addr ffff888014941048 by task xfs_io/27534    CPU: 0 PID: 27534 Comm: xfs_io Not tainted 6.6.0-rc7 #1   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS   rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014   Call Trace:    dump_stack_lvl+0x4a/0x80    print_report+0xcf/0x650    ? srso_alias_return_thunk+0x5/0x7f    ? srso_alias_return_thunk+0x5/0x7f    ? __phys_addr+0x46/0x90    kasan_report+0xda/0x110    ? smb2_query_info_compound+0x423/0x6d0 [cifs]    ? smb2_query_info_compound+0x423/0x6d0 [cifs]    smb2_query_info_compound+0x423/0x6d0 [cifs]    ? __pfx_smb2_query_info_compound+0x10/0x10 [cifs]    ? srso_alias_return_thunk+0x5/0x7f    ? __stack_depot_save+0x39/0x480    ? kasan_save_stack+0x33/0x60    ? kasan_set_track+0x25/0x30    ? ____kasan_slab_free+0x126/0x170    smb2_queryfs+0xc2/0x2c0 [cifs]    ? __pfx_smb2_queryfs+0x10/0x10 [cifs]    ? __pfx___lock_acquire+0x10/0x10    smb311_queryfs+0x210/0x220 [cifs]    ? __pfx_smb311_queryfs+0x10/0x10 [cifs]    ? srso_alias_return_thunk+0x5/0x7f    ? __lock_acquire+0x480/0x26c0    ? lock_release+0x1ed/0x640    ? srso_alias_return_thunk+0x5/0x7f    ? do_raw_spin_unlock+0x9b/0x100    cifs_statfs+0x18c/0x4b0 [cifs]    statfs_by_dentry+0x9b/0xf0    fd_statfs+0x4e/0xb0    __do_sys_fstatfs+0x7f/0xe0    ? __pfx___do_sys_fstatfs+0x10/0x10    ? srso_alias_return_thunk+0x5/0x7f    ? lockdep_hardirqs_on_prepare+0x136/0x200    ? srso_alias_return_thunk+0x5/0x7f    do_syscall_64+0x3f/0x90    entry_SYSCALL_64_after_hwframe+0x6e/0xd8    Allocated by task 27534:    kasan_save_stack+0x33/0x60    kasan_set_track+0x25/0x30    __kasan_kmalloc+0x8f/0xa0    open_cached_dir+0x71b/0x1240 [cifs]    smb2_query_info_compound+0x5c3/0x6d0 [cifs]    smb2_queryfs+0xc2/0x2c0 [cifs]    smb311_queryfs+0x210/0x220 [cifs]    cifs_statfs+0x18c/0x4b0 [cifs]    statfs_by_dentry+0x9b/0xf0    fd_statfs+0x4e/0xb0    __do_sys_fstatfs+0x7f/0xe0    do_syscall_64+0x3f/0x90    entry_SYSCALL_64_after_hwframe+0x6e/0xd8    Freed by task 27534:    kasan_save_stack+0x33/0x60    kasan_set_track+0x25/0x30    kasan_save_free_info+0x2b/0x50    ____kasan_slab_free+0x126/0x170    slab_free_freelist_hook+0xd0/0x1e0    __kmem_cache_free+0x9d/0x1b0    open_cached_dir+0xff5/0x1240 [cifs]    smb2_query_info_compound+0x5c3/0x6d0 [cifs]    smb2_queryfs+0xc2/0x2c0 [cifs]  This is a race between open_cached_dir() and cached_dir_lease_break() where the cache entry for the open directory handle receives a lease break while creating it.  And before returning from open_cached_dir(), we put the last reference of the new @cfid because of !@cfid->has_lease.  Besides the UAF, while running xfstests a lot of missed lease breaks have been noticed in tests that run several concurrent statfs(2) calls on those cached fids    CIFS: VFS: \\w22-root1.gandalf.test No task to wake, unknown frame...   CIFS: VFS: \\w22-root1.gandalf.test Cmd: 18 Err: 0x0 Flags: 0x1...   CIFS: VFS: \\w22-root1.gandalf.test smb buf 00000000715bfe83 len 108   CIFS: VFS: Dump pending requests:   CIFS: VFS: \\w22-root1.gandalf.test No task to wake, unknown frame...   CIFS: VFS: \\w22-root1.gandalf.test Cmd: 18 Err: 0x0 Flags: 0x1...   CIFS: VFS: \\w22-root1.gandalf.test smb buf 000000005aa7316e len 108   ...  To fix both, in open_cached_dir() ensure that @cfid->has_lease is set right before sending out compounded request so that any potential lease break will be get processed by demultiplex thread while we're still caching @cfid.  And, if open failed for some reason, re-check @cfid->has_lease to decide whether or not put lease reference.