From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 907841527AC; Fri, 6 Dec 2024 15:18:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733498298; cv=none; b=adriD5ll6OGF/60p9AsHhkRy1YOk/M0oIDqlBaISJG0WryOA8+TJtqa2yvPSv6IoQVsnSfaLX+LsllX9J8ujX6OHtvpGtQEP4vJ93hDCsz9lIvVDdO0vFKbp9ERQLriHziCmgnsZUrBK5zmlhChSn91CsnH+lGyZQWySQDclh9I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733498298; c=relaxed/simple; bh=Y8ftVIwwbncsJhL5HC7LCtCjrMV+bUiTmwvecE6wcgI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p0SWMpCtaHBLD5pEbpjSonN0Urlc0fapmpWVv9lTvyOdhVbRjUliOu8Y52CCf4dAjrtiR2VhtNZzwwJmBh4anNO4ifhOTHRCR98i3MZ+wemZwJi/6P7TE6BO5o+7vfOIAGnLhVoy5UkCfK+1FLf1X0P8LvN9BiehFCnILSvxMzY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jSz6uZBz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jSz6uZBz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6CF4C4CED1; Fri, 6 Dec 2024 15:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1733498298; bh=Y8ftVIwwbncsJhL5HC7LCtCjrMV+bUiTmwvecE6wcgI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jSz6uZBz74OvW8rY17Q+BVb107p1008EhqQZGUtBslV625abQpOpfDsJAXuZLyFTB gOicBDP8cAxVJ22y1uMIbMpGZf8gSB8WpNlWg1i4S5/8+SkJr+A0sdoGHVym8dbFFS p0inTzvzYrASLGNwML6NzbmX0nydq2xpcktiO91c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Paul Aurich , Steve French Subject: [PATCH 6.6 543/676] smb: prevent use-after-free due to open_cached_dir error paths Date: Fri, 6 Dec 2024 15:36:02 +0100 Message-ID: <20241206143714.569336809@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241206143653.344873888@linuxfoundation.org> References: <20241206143653.344873888@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Aurich commit a9685b409a03b73d2980bbfa53eb47555802d0a9 upstream. 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: 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 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@vger.kernel.org Signed-off-by: Paul Aurich Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cached_dir.c | 70 ++++++++++++++++++--------------------------- 1 file changed, 29 insertions(+), 41 deletions(-) --- a/fs/smb/client/cached_dir.c +++ b/fs/smb/client/cached_dir.c @@ -348,6 +348,7 @@ oshr_free: SMB2_query_info_free(&rqst[1]); free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base); free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base); +out: if (rc) { spin_lock(&cfids->cfid_list_lock); if (cfid->on_list) { @@ -359,23 +360,14 @@ oshr_free: /* * We are guaranteed to have two references at this * point. One for the caller and one for a potential - * lease. Release the Lease-ref so that the directory - * will be closed when the caller closes the cached - * handle. + * lease. Release one here, and the second below. */ cfid->has_lease = false; - spin_unlock(&cfids->cfid_list_lock); kref_put(&cfid->refcount, smb2_close_cached_fid); - goto out; } spin_unlock(&cfids->cfid_list_lock); - } -out: - if (rc) { - if (cfid->is_open) - SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid, - cfid->fid.volatile_fid); - free_cached_dir(cfid); + + kref_put(&cfid->refcount, smb2_close_cached_fid); } else { *ret_cfid = cfid; atomic_inc(&tcon->num_remote_opens); @@ -513,25 +505,24 @@ void invalidate_all_cached_dirs(struct c cfids->num_entries--; cfid->is_open = false; cfid->on_list = false; - /* To prevent race with smb2_cached_lease_break() */ - kref_get(&cfid->refcount); + if (cfid->has_lease) { + /* + * The lease was never cancelled from the server, + * so steal that reference. + */ + cfid->has_lease = false; + } else + kref_get(&cfid->refcount); } spin_unlock(&cfids->cfid_list_lock); list_for_each_entry_safe(cfid, q, &entry, entry) { list_del(&cfid->entry); cancel_work_sync(&cfid->lease_break); - if (cfid->has_lease) { - /* - * We lease was never cancelled from the server so we - * need to drop the reference. - */ - spin_lock(&cfids->cfid_list_lock); - cfid->has_lease = false; - spin_unlock(&cfids->cfid_list_lock); - kref_put(&cfid->refcount, smb2_close_cached_fid); - } - /* Drop the extra reference opened above*/ + /* + * Drop the ref-count from above, either the lease-ref (if there + * was one) or the extra one acquired. + */ kref_put(&cfid->refcount, smb2_close_cached_fid); } } @@ -542,9 +533,6 @@ smb2_cached_lease_break(struct work_stru struct cached_fid *cfid = container_of(work, struct cached_fid, lease_break); - spin_lock(&cfid->cfids->cfid_list_lock); - cfid->has_lease = false; - spin_unlock(&cfid->cfids->cfid_list_lock); kref_put(&cfid->refcount, smb2_close_cached_fid); } @@ -562,6 +550,7 @@ int cached_dir_lease_break(struct cifs_t !memcmp(lease_key, cfid->fid.lease_key, SMB2_LEASE_KEY_SIZE)) { + cfid->has_lease = false; cfid->time = 0; /* * We found a lease remove it from the list @@ -639,8 +628,14 @@ static void cfids_laundromat_worker(stru cfid->on_list = false; list_move(&cfid->entry, &entry); cfids->num_entries--; - /* To prevent race with smb2_cached_lease_break() */ - kref_get(&cfid->refcount); + if (cfid->has_lease) { + /* + * Our lease has not yet been cancelled from the + * server. Steal that reference. + */ + cfid->has_lease = false; + } else + kref_get(&cfid->refcount); } } spin_unlock(&cfids->cfid_list_lock); @@ -652,17 +647,10 @@ static void cfids_laundromat_worker(stru * with it. */ cancel_work_sync(&cfid->lease_break); - if (cfid->has_lease) { - /* - * Our lease has not yet been cancelled from the server - * so we need to drop the reference. - */ - spin_lock(&cfids->cfid_list_lock); - cfid->has_lease = false; - spin_unlock(&cfids->cfid_list_lock); - kref_put(&cfid->refcount, smb2_close_cached_fid); - } - /* Drop the extra reference opened above */ + /* + * Drop the ref-count from above, either the lease-ref (if there + * was one) or the extra one acquired. + */ kref_put(&cfid->refcount, smb2_close_cached_fid); } queue_delayed_work(cifsiod_wq, &cfids->laundromat_work,