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=1793663403; b=dxLF7GWqDnoO1j+zAedCS6/SsbapP33z5IxOOZ4rsKoNVWUc4cm2402imuYdlY92LVfh eV+erWQ1yjEhLX9j0z3NAeuP0osnwQ+sQpo0VDnkwBNNPgezzeraf1lDXRPZbZbcMO9/G yNxB118F6zcXiKCeFIm+QIBwqJ/qeBrS8Fi7l3qsAEuIbztE6usIjjMGOkmqakTxmQUlx 10Xq2MzL09QpBVpTWcwxCOQcrFBdnw4ka0nnHgoSU6SPna8oahdWDfIepCuuAoOLs8QVS camIEJXjzPHLsbyvOYkv8qtC5mqIKH3B+igicWnRyWbNqAjSLmcZsQbVVimTErjSASw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793663403; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=/wXgkfJ4QQYFajApB1Bfjjp05dvHcixqbWmk/1JD90M=; b=oGVzBUtlvmyNRNScUnp62gwEdqigmKBNGQ4IvOHlUza73taTWKgr379g/9Gq3e5EsqJE eFnt7+Q+cs3rDk2sQc55sc7fbyAPWumm1mbOWe2J2WD3ktOxmVXi1BQVxaVZZX1fHIHTA /mEWoc5hTRE3iRMp7k+pbjKfDbjNDkFSkD3IMVJxC98isutwREFZmUVnOuSRahnbW7ZcQ UHMuDCMSHYO+9QNZB9/q8th8bQi5bzskF6LPa6zKticW0cCT3zLlkooZHBhtFbf+umpJn HNfj29AnFbha6LITh5QnXR87iXVLi59/QZ8pf34cFKlMpMsR4o6qxREH15+oCX4UpFA== 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=PKtww8X6; 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 6751B606A33B for ; Mon, 2 Nov 2026 23:50:03 +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=PKtww8X6 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B99FC1F00A16; Mon, 2 Nov 2026 23:50:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793663403; bh=/wXgkfJ4QQYFajApB1Bfjjp05dvHcixqbWmk/1JD90M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PKtww8X6d6kBwEBKiRdUyF9L/e5E1iFqgFkNon/TQ2vRs0vLy72ZZK+vvOEnr62DB SpvizCPhdeVCjcjWL56FqlwIK1XTNqYg88OwWlaxgAFHPzVL4ScRwqy7Dn5WJWBQT/ UPWm+IU7CUAGsrDvDiXDaHA58R8G6lQBUY1+7d4HBpHnM5QTqweW2zMAn78K0L90gl Ui9q6pUvi+KaSVRvl3j0diO8wMzmIVd2QRVc0E2TimAuFTdRqEKxL5iYtbwBJiVKlZ hGbOo9HBdqKk6QCcsYPNUxkZQKwlI9idI/kmeiCdEjn8mgVLwcu4H03KcvQ3GfP1ei ZVd0BOUYuM9Pg== From: Sasha Levin To: stable@vger.kernel.org Cc: Fredric Cover , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.6.y] smb: client: fix early procfs exposure race Date: Mon, 2 Nov 2026 18:50:01 -0500 Message-ID: <20261102234411.2558907-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110228-badge-squeak-7e20@gregkh> References: <2026110228-badge-squeak-7e20@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 init_cifs() context for different initialization code and workqueue allocation 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 3154b21bfe8a2..37929590b77c4 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1848,7 +1848,6 @@ static int __init init_cifs(void) { int rc = 0; - cifs_proc_init(); INIT_LIST_HEAD(&cifs_tcp_ses_list); /* * Initialize Global counters @@ -1897,10 +1896,8 @@ 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) @@ -1983,19 +1980,22 @@ 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 @@ -2029,8 +2029,6 @@ init_cifs(void) destroy_workqueue(decrypt_wq); out_destroy_cifsiod_wq: destroy_workqueue(cifsiod_wq); -out_clean_proc: - cifs_proc_clean(); return rc; } @@ -2040,6 +2038,7 @@ 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 @@ -2061,7 +2060,6 @@ 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