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=1793672545; b=jj/Wl1bRwWwqrikAFaB2agwHQXlVquh8Xsc+8/DnG1B8KEKIkD3V3GthVUXseHCFMFJQ 4vK18G0KSzIWC0xzIR3zwWA97v7Aov4UhHgCC8m9jFzJIdW+SXoBDNQRsPnIfzwXF9JdH goZWqkHABklh3lMA7jmVooHo4ogirfIlUBKYHlLh6m3TCjniahN2GBg9+LQyt6Q4LwQS5 AmGv1Yr+RO01lXBBHRdVO7+dvtYqtSw/UVUOJ6SKkPQBbPmEUYo2d9Bnan9OJn3Zs5bvJ ZzyVotbncO+rUj11+M3i6lhUBB/zkj14sse+0OAPvg55ZbQTfgTa9hiyLeoZ2aLLh+A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793672545; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=NUUpVkuu2VvZEInR5XBa9ztNnNOfurmbvcEuNADRsb4=; b=o9dYzRwXhOzrnUM1BTgDdzkDfoRqyE6PAZHelU27X+a6uNZMPLBsD+/3fgBS05Dlkind g3TwQMdHRXfyWP80rqYDtXljmUB57/apZTqAQYrmtZEegpFkjCq1IjpD6Ii6dU87CbEuB qYWjixsd4ScpNBhl+SOfVk+JmiXh8+hbiV3WeLeSWmceE3BgeAXPXv3fzKLZisFV6H4xW ZLJ9EMdrP57dHWy0Run0isI2kJDhpO/XthGJGZ5Rv6D7OMlx9YWBFzlVdzcrkgn5br3U0 EScdh33cEIRzLNYcDHV4x+NEq3imbLYPthhOcwsRuCYmF7QjPGx8g0+WMI72I7UdN4g== 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=ljmFsSAB; 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 6CEA4606A32D for ; Tue, 3 Nov 2026 02:22:25 +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=ljmFsSAB Received: by smtp.kernel.org (Postfix) with ESMTPSA id C559E1F00A15; Tue, 3 Nov 2026 02:22:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793672545; bh=NUUpVkuu2VvZEInR5XBa9ztNnNOfurmbvcEuNADRsb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ljmFsSABl5CLi2hbY8vLTh6taqvG0YXmKByTTLtQ6PhA42bs0brK0H2E1Ajonu/Wk Pd2nwY0pb8TvTG5MrPg2RE7vU3sxnshGPOxJTeVwUqMruQAy/mq1YRCeGUSBoUj6d4 A2o42Ecc6zNFCxkXRgLTrRZqr5v3L7j9fKUsyRKSDMqlmtijQeHJnhwdZjzSVBnPbm 24SJSwyuNzdrebCyGDRfy6N8fYiasHMZigKOSi6i//spUxCegMPrFzmZpIjfV62kyX Sf6tuyPVw12gCwCHpP9e5Hua8W5QEy04UNUAvv3iiNEgHAG0vTBNlRpCemEOW8SMHB bfWPoyTbHRABQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Fredric Cover , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.1.y] smb: client: fix early procfs exposure race Date: Mon, 2 Nov 2026 21:22:23 -0500 Message-ID: <20261103020041.2820524-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110229-bath-sphere-8a84@gregkh> References: <2026110229-bath-sphere-8a84@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-Type: text/plain; charset=UTF-8 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 to fit the existing CIFS initialization and teardown code while preserving upstream’s added and removed lines. ] 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 d369528532c39..60ec559e0b6da 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1842,7 +1842,6 @@ static int __init init_cifs(void) { int rc = 0; - cifs_proc_init(); INIT_LIST_HEAD(&cifs_tcp_ses_list); /* * Initialize Global counters @@ -1885,10 +1884,8 @@ 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) @@ -1964,19 +1961,22 @@ 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 @@ -2008,8 +2008,6 @@ init_cifs(void) destroy_workqueue(decrypt_wq); out_destroy_cifsiod_wq: destroy_workqueue(cifsiod_wq); -out_clean_proc: - cifs_proc_clean(); return rc; } @@ -2019,6 +2017,7 @@ exit_cifs(void) cifs_dbg(NOISY, "exit_smb3\n"); unregister_filesystem(&cifs_fs_type); unregister_filesystem(&smb3_fs_type); + cifs_proc_clean(); cifs_dfs_release_automount_timer(); exit_cifs_idmap(); #ifdef CONFIG_CIFS_SWN_UPCALL @@ -2039,7 +2038,6 @@ exit_cifs(void) destroy_workqueue(fileinfo_put_wq); destroy_workqueue(serverclose_wq); destroy_workqueue(cifsiod_wq); - cifs_proc_clean(); } MODULE_AUTHOR("Steve French"); -- 2.53.0