From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793660458; b=yVBqXjM4a9sSd06JHJBvxnihHI9qM+gSFDBgzKxI5cLsD9whY/QyAODn5ORl/iGJ6C4k 64z+FHii9d7147BZCSBcGRwR9Cm6hFNH7MTyuscWY4pTzzLHQhFMUzFLvBjhWVZf6IL+E gKGH+2hK4E69OEIEdCk8S4tHTS+ZWWzHxeOaoverggcqZvRcC7MYZSKDbXNzB9dCY4kAM zAhQJ3kR/LBsvay03Ephd9Ss3Y3+AjjceC4OwEgRPI0xvO8P3GoIoGLXhUYml5NMB1joD l7uzUxi2vXN+9xtRfQHMV32eOY1cPQnPDmAjJRklM2V9DoqQBA7SmcTjYMMPjyaI1CA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793660458; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=v9FoiQ0Bda4AOHHLTuZWnGDukyDMUCFy7/0BGVhTX3c=; b=eO6iJk+JremMOFASMaoCK9XYAleAiwnIvWt5OCNlK9evPGBGpgl8EJJ6mNz+xGLFpNgr LDSgRm1Ui7t0tg2nylIGUU9o2irCuP3Qgqiif+nYnDW0jCPLU8h2KNpe2FHYvcE0Or1xw hq9ychv4/MmUEAAvqHRCQjn68PQ+rVF8sTE4rDtVadqtMz0jgDKTRJk8Ut1xs+OdNkppV bTgULEHly2b+XPtPgsn9pUEX8dc6CTliLIpLAV7SuriT2aGqfNbVvgAnuTb6snQWx/+Kp guA2yCvHiE0gYHoUowy8vM5pvdaWK46Pd2wvMwe2lhP/WOz2ndpVhKiGkpcbOLMFUig== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Y5qqVcRR; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 280A3606A326 for ; Mon, 2 Nov 2026 23:00:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Y5qqVcRR Received: by smtp.kernel.org (Postfix) with ESMTPSA id 290E21F00A16; Mon, 2 Nov 2026 23:00:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793660457; bh=v9FoiQ0Bda4AOHHLTuZWnGDukyDMUCFy7/0BGVhTX3c=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Y5qqVcRRMvYLXBarndxslkTMxmRbLi0ynatcrY+C3eel70HvT7i/jM5vijtb8wH6z +MqNP41mN+L+IrgEjzH3Z1HBZVN1AIlAp1/W/0GyDtSndh/pwkclBqBtQddLPcPyX3 0ZGka5EA5HlJqDmmFseFhDOdYgNpJGPap5RVstueW1+0MP2GaOAFk6Hr2QD1Yl2Ae9 ZVV1tZAZ/17XEUI1LxMaIIknS7PpYyfJHdRH7DjEDkrcC+qYYhd4EUG+q5OgcQePtS oUvcUMBJENFLo4StuSPBlliWGp0oHQH6EHGYDl6n81Hc7KV8gpBEHsjZt8ZTEZ0Q1Y EbFpP2FTtblBA== From: Sasha Levin To: stable@vger.kernel.org Cc: Fredric Cover , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.12.y] smb: client: fix early procfs exposure race Date: Mon, 2 Nov 2026 18:00:55 -0500 Message-ID: <20261102223800.2124716-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110227-triumph-worry-bc74@gregkh> References: <2026110227-triumph-worry-bc74@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Fredric Cover [ Upstream commit 7b1afb631395c958993cda4631002258ef4151ea ] Currently, init_cifs() calls cifs_proc_init() near the beginning of the function, before INIT_LIST_HEAD, leading to a momentarily uninitialized, but exposed, procfs. If a userspace process reads this empty procfs, iterating over a zeroed list_head leads to a NULL pointer dereference and a kernel oops/panic. For example, if a delay is added between cifs_proc_init() and INIT_LIST_HEAD, and a userspace process is polling /proc/fs/cifs/DebugData, the following oops occurs: BUG: kernel NULL pointer dereference, address: 0000000000000608 Oops: Oops: 0000 [#1] SMP PTI CPU: 0 UID: 0 PID: 3477 Comm: cat Not tainted 7.3.0-02212-g4df4d2a577db-dirty #6 PREEMPT(lazy) RIP: 0010:cifs_debug_data_proc_show+0x103/0xd80 [cifs] Call Trace: ? seq_read_iter+0x86/0x400 ? seq_read_iter+0x86/0x400 seq_read_iter+0x183/0x400 proc_reg_read_iter+0x62/0x90 copy_splice_read+0x215/0x310 splice_file_to_pipe+0xec/0x1c0 do_splice+0x4b8/0x780 __se_sys_splice+0x18f/0x250 do_syscall_64+0x109/0x330 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by moving cifs_proc_init() down in init_cifs(), ensuring it runs only after all internal lists, locks, counters, and workqueues are fully ready, but before registering the filesystem. Update the error cleanup ladder and exit_cifs() to maintain proper LIFO order. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Fredric Cover Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara [ sashal: Adjusted context for absent maperror initialization calls and a workqueue declaration without WQ_PERCPU. ] Signed-off-by: Sasha Levin --- fs/smb/client/cifsfs.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c index 65bf11f606ed4..cfe950e3fb9cf 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1916,7 +1916,6 @@ static int __init init_cifs(void) { int rc = 0; - cifs_proc_init(); INIT_LIST_HEAD(&cifs_tcp_ses_list); /* * Initialize Global counters @@ -1965,10 +1964,8 @@ init_cifs(void) } cifsiod_wq = alloc_workqueue("cifsiod", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0); - if (!cifsiod_wq) { - rc = -ENOMEM; - goto out_clean_proc; - } + if (!cifsiod_wq) + return -ENOMEM; /* * Consider in future setting limit!=0 maybe to min(num_of_cores - 1, 3) @@ -2055,19 +2052,22 @@ init_cifs(void) if (rc) goto out_cifs_swn_init; + cifs_proc_init(); + rc = register_filesystem(&cifs_fs_type); if (rc) - goto out_init_cifs_idmap; + goto out_clean_proc; rc = register_filesystem(&smb3_fs_type); if (rc) { unregister_filesystem(&cifs_fs_type); - goto out_init_cifs_idmap; + goto out_clean_proc; } return 0; -out_init_cifs_idmap: +out_clean_proc: + cifs_proc_clean(); exit_cifs_idmap(); out_cifs_swn_init: #ifdef CONFIG_CIFS_SWN_UPCALL @@ -2103,8 +2103,6 @@ init_cifs(void) destroy_workqueue(decrypt_wq); out_destroy_cifsiod_wq: destroy_workqueue(cifsiod_wq); -out_clean_proc: - cifs_proc_clean(); return rc; } @@ -2114,6 +2112,7 @@ exit_cifs(void) cifs_dbg(NOISY, "exit_smb3\n"); unregister_filesystem(&cifs_fs_type); unregister_filesystem(&smb3_fs_type); + cifs_proc_clean(); cifs_release_automount_timer(); exit_cifs_idmap(); #ifdef CONFIG_CIFS_SWN_UPCALL @@ -2136,7 +2135,6 @@ exit_cifs(void) destroy_workqueue(serverclose_wq); destroy_workqueue(cfid_put_wq); destroy_workqueue(cifsiod_wq); - cifs_proc_clean(); } MODULE_AUTHOR("Steve French"); -- 2.53.0