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=1793657707; b=u/mHCcggiux7TragfPnkAsyL2bLJIu6yEvDvuk4JLzrirSFjCwQ/RYGr52WlQl0mz3uQ NkHH8DDz0QN5c5wHLiIebHaracmLAD6/pKiOF/Ygqu/WYM096A8ROFWnWly8XPTDICUlA V83WolnbTWxOZP7LLdmE9yA2GRG6PWZHn1c/7gePbJR2Y6cmnoKLMMJbMp4z6cuGeBjmw WkM+CuC4ZqJJk9kwo7e/eGUKxhdIRsH5fe+d+2JenWifAVAszX6G4FAcJEyQ/mpYP6r3R 88OY/S1xdqUFnXQIYJXj3+tMzB4Hoy6IVtt3qO8x9wi3oHTH6qlDyzhhnnlj2NxOh7w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793657707; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=iqaluuXLU0P5v8XKBT390cdLc5CuEh0nbitnp1+hGq0=; b=LQnbcx2FXLPEkl6NW6oq9NL5SoxgsUG+PywgAAm5px4+90+9aBPB5lLNiG8h3kEnpkQs HRf84WVpyHNBXh4xSeRoxqNDioye7IVDRqj4Fj8vugwx0dGJrnDh5V5BwEMb/s/ByruKB uic/WH40bS/IEKufa6/qMbkfjnIIMBJ+nG3nnMxfcuDKEgWO9AXIQvYu+YhvGXzZ2R6kX weiDAZpGyCG0nQav9O2I9AR8aP/vrShOZEkGwid2TxFZ3E9CS5IPuHcDPSsXx5UOpX8g5 A3oc/e8VVRE/5eANbYRzBcpQfDaJpw8KEKY+pASVQnOUHMXqx9CMg376UYQ5dd7Zh2g== 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=i2WzsNdY; 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 B2545606A329 for ; Mon, 2 Nov 2026 22:15:06 +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=i2WzsNdY Received: by smtp.kernel.org (Postfix) with ESMTPSA id D39B11F00A16; Mon, 2 Nov 2026 22:15:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793657706; bh=iqaluuXLU0P5v8XKBT390cdLc5CuEh0nbitnp1+hGq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=i2WzsNdYZtJSlGGafY0AZ3iAN0ywKM2rbssqGuCTUYBssXwd88HH8SH2UCaLLf7UN 1+tSrj1zQPB9zFw5RMKe7kkt6QvvGU4oMZx/Gbk/jVbbX2B/fUTZbk3r7MhbchQvdc FPmt0PoRqJMhr1SzSzkzoT9RfCV4qy2f5kNQieH+uDNYf/tmaCu7F17Y1bHNUhl0kI hlugSGoss7minuBKXg5G6HelQIAZdZOD8wMdVvY1sY4pILodfYUT37DpzSJldoOC+Q V6SnWbuNcHe/Hx3DcmdY6nFqWYmfNTSfjzNnpIIm6PM8pubEYdSI3s2D+kiqQQMX12 WsiHz7UaXGXhw== From: Sasha Levin To: stable@vger.kernel.org Cc: Fredric Cover , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.18.y] smb: client: fix early procfs exposure race Date: Mon, 2 Nov 2026 17:15:04 -0500 Message-ID: <20261102221432.1871440-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110226-gigantic-arson-32db@gregkh> References: <2026110226-gigantic-arson-32db@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 because smb1_init_maperror() and smb2_init_maperror() are absent. ] 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 23ec5c3666d3d..3da0fc08ffd94 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1972,7 +1972,6 @@ static int __init init_cifs(void) { int rc = 0; - cifs_proc_init(); INIT_LIST_HEAD(&cifs_tcp_ses_list); /* * Initialize Global counters @@ -2021,10 +2020,8 @@ init_cifs(void) cifsiod_wq = alloc_workqueue("cifsiod", WQ_FREEZABLE | WQ_MEM_RECLAIM | WQ_PERCPU, 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) @@ -2115,19 +2112,22 @@ 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 @@ -2163,8 +2163,6 @@ init_cifs(void) destroy_workqueue(decrypt_wq); out_destroy_cifsiod_wq: destroy_workqueue(cifsiod_wq); -out_clean_proc: - cifs_proc_clean(); return rc; } @@ -2174,6 +2172,7 @@ 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 @@ -2196,7 +2195,6 @@ 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