linux-kernel - Re: [PATCH 6.1.y] smb: prevent use-after-free due to open_cached

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Message-ID: <4a248d5e-fb81-4f45-aaec-79c36f93e14b@windriver.com>
Date: Thu, 20 Mar 2025 10:12:54 +0800
From: Cliff Liu <donghua.liu@...driver.com>
To: Greg KH <gregkh@...uxfoundation.org>, Sasha Levin <sashal@...nel.org>,
        stable@...r.kernel.org
Cc: sfrench@...ba.org, pc@....nz, lsahlber@...hat.com, sprasad@...rosoft.com,
        tom@...pey.com, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
        paul@...krain42.org, Zhe.He@...driver.com
Subject: Re: [PATCH 6.1.y] smb: prevent use-after-free due to open_cached_dir
 error paths

Hi,

There is upstream id in my local patch, but it is discarded by 'git 
shend-mail'.

Please ignore this patch. I'll check the reason and send it later.

So sorry for my mistake.

Thanks,

   Cliff

On 2025/3/19 22:03, Greg KH wrote:
> CAUTION: This email comes from a non Wind River email account!
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> On Wed, Mar 19, 2025 at 05:08:39PM +0800, Cliff Liu wrote:
>> From: Paul Aurich <paul@...krain42.org>
>>
>> If open_cached_dir() encounters an error parsing the lease from the
>> server, the error handling may race with receiving a lease break,
>> resulting in open_cached_dir() freeing the cfid while the queued work is
>> pending.
>>
>> Update open_cached_dir() to drop refs rather than directly freeing the
>> cfid.
>>
>> Have cached_dir_lease_break(), cfids_laundromat_worker(), and
>> invalidate_all_cached_dirs() clear has_lease immediately while still
>> holding cfids->cfid_list_lock, and then use this to also simplify the
>> reference counting in cfids_laundromat_worker() and
>> invalidate_all_cached_dirs().
>>
>> Fixes this KASAN splat (which manually injects an error and lease break
>> in open_cached_dir()):
>>
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in smb2_cached_lease_break+0x27/0xb0
>> Read of size 8 at addr ffff88811cc24c10 by task kworker/3:1/65
>>
>> CPU: 3 UID: 0 PID: 65 Comm: kworker/3:1 Not tainted 6.12.0-rc6-g255cf264e6e5-dirty #87
>> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
>> Workqueue: cifsiod smb2_cached_lease_break
>> Call Trace:
>>   <TASK>
>>   dump_stack_lvl+0x77/0xb0
>>   print_report+0xce/0x660
>>   kasan_report+0xd3/0x110
>>   smb2_cached_lease_break+0x27/0xb0
>>   process_one_work+0x50a/0xc50
>>   worker_thread+0x2ba/0x530
>>   kthread+0x17c/0x1c0
>>   ret_from_fork+0x34/0x60
>>   ret_from_fork_asm+0x1a/0x30
>>   </TASK>
>>
>> Allocated by task 2464:
>>   kasan_save_stack+0x33/0x60
>>   kasan_save_track+0x14/0x30
>>   __kasan_kmalloc+0xaa/0xb0
>>   open_cached_dir+0xa7d/0x1fb0
>>   smb2_query_path_info+0x43c/0x6e0
>>   cifs_get_fattr+0x346/0xf10
>>   cifs_get_inode_info+0x157/0x210
>>   cifs_revalidate_dentry_attr+0x2d1/0x460
>>   cifs_getattr+0x173/0x470
>>   vfs_statx_path+0x10f/0x160
>>   vfs_statx+0xe9/0x150
>>   vfs_fstatat+0x5e/0xc0
>>   __do_sys_newfstatat+0x91/0xf0
>>   do_syscall_64+0x95/0x1a0
>>   entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> Freed by task 2464:
>>   kasan_save_stack+0x33/0x60
>>   kasan_save_track+0x14/0x30
>>   kasan_save_free_info+0x3b/0x60
>>   __kasan_slab_free+0x51/0x70
>>   kfree+0x174/0x520
>>   open_cached_dir+0x97f/0x1fb0
>>   smb2_query_path_info+0x43c/0x6e0
>>   cifs_get_fattr+0x346/0xf10
>>   cifs_get_inode_info+0x157/0x210
>>   cifs_revalidate_dentry_attr+0x2d1/0x460
>>   cifs_getattr+0x173/0x470
>>   vfs_statx_path+0x10f/0x160
>>   vfs_statx+0xe9/0x150
>>   vfs_fstatat+0x5e/0xc0
>>   __do_sys_newfstatat+0x91/0xf0
>>   do_syscall_64+0x95/0x1a0
>>   entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> Last potentially related work creation:
>>   kasan_save_stack+0x33/0x60
>>   __kasan_record_aux_stack+0xad/0xc0
>>   insert_work+0x32/0x100
>>   __queue_work+0x5c9/0x870
>>   queue_work_on+0x82/0x90
>>   open_cached_dir+0x1369/0x1fb0
>>   smb2_query_path_info+0x43c/0x6e0
>>   cifs_get_fattr+0x346/0xf10
>>   cifs_get_inode_info+0x157/0x210
>>   cifs_revalidate_dentry_attr+0x2d1/0x460
>>   cifs_getattr+0x173/0x470
>>   vfs_statx_path+0x10f/0x160
>>   vfs_statx+0xe9/0x150
>>   vfs_fstatat+0x5e/0xc0
>>   __do_sys_newfstatat+0x91/0xf0
>>   do_syscall_64+0x95/0x1a0
>>   entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> The buggy address belongs to the object at ffff88811cc24c00
>>   which belongs to the cache kmalloc-1k of size 1024
>> The buggy address is located 16 bytes inside of
>>   freed 1024-byte region [ffff88811cc24c00, ffff88811cc25000)
>>
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Paul Aurich <paul@...krain42.org>
>> Signed-off-by: Steve French <stfrench@...rosoft.com>
>> [ Do not apply the change for cfids_laundromat_worker() since there is no
>>    this function and related feature on 6.1.y. Update open_cached_dir()
>>    according to method of upstream patch. ]
>> Signed-off-by: Cliff Liu <donghua.liu@...driver.com>
>> Signed-off-by: He Zhe <Zhe.He@...driver.com>
>> ---
>> Verified the build test.
>> ---
>>   fs/smb/client/cached_dir.c | 39 ++++++++++++++++----------------------
>>   1 file changed, 16 insertions(+), 23 deletions(-)
> No upstream git id :(