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=1793831947; b=YhCs0Z/ZWD6P2u8SPnc/3NdMwdEgm3v38zR0Sl0mIe9692plBJeekkjkvcJH0qlIR+fH zo74sJEhURUVaUH4OHSAOVQJvl0exvXPDGA3yJAyG53jc0cz6yxhhzdOi5A+NFTIUwvD+ bCrJvhSz/j0bVxb1GMGFd/a8Zx2m6pKmnxFP66QUcDbKH/rnuoMl0XdMUlgjrP58+6RdR 3MweL3TMw45tvqAOfcB2Cvh2r9s1Qkw/eM13kLaJF9bPqTsMNyYIaDlpiBZH6DxexMIRW jgiRdzjTDIMf/g8YNNNQJjmxgxaevfl+eesvxpIfYoeRSaxDLPupBNgGuGIFh+yV2+g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831947; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=KfNKa79znQ4PymwOhmCfa4nIs0CYHTlrFcc/UixLxrY=; b=ktPwBnsa2m83tL7UYPKtZHWkaQEm8jSn5yUseL5gQGDIDHxjN9QZRwHp9GT1m1i46aDj Rub9oxn/iaT68v88CvWFH84h4dlhf/0bjYWGr+aHfaNVOVNzTCOyCqGcHuFwJi11YmXi0 DGS652RPWel6MRpFZ1lI/PUGaKPM0niI0ts2tiNEE1mcXforpkdUBOTo+ERotjvp7Vgfr caLB1XD+LqMPfk0835hAGWUM/uabfGT/6geldkHDQcg9VLibcvZreFVyMZGdC/VR/f4sL UTgC42NWQFxKItbtFStrHyUmS35DtX9Fzz51ytC0qrUTZhm6DBMDwY12W6FmEJCG5mw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2jeYu9Qa; 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 0E2B1606A85B; Wed, 4 Nov 2026 22:39:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2jeYu9Qa Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75FF31F00919; Wed, 4 Nov 2026 22:39:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831946; bh=KfNKa79znQ4PymwOhmCfa4nIs0CYHTlrFcc/UixLxrY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2jeYu9QalZrQG/UXZA85F/WfQhZ7+FBoKI6fOzAsdh3s9XfpFQmpXXX+CWf9/y2bM 13mWvEDnfJPPJTrCPizY6K4BNWacFBhC4Y6O+cDU/EH8wYDOPVd7NT/Kylsiq1YSV2 Ap0Hn8Du6Iu1ZiWV2hSk2kU12dJmPuSstB/ZDrMc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fredric Cover , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.18 0983/1005] smb: client: fix early procfs exposure race Date: Wed, 4 Nov 2026 16:11:56 -0500 Message-ID: <20261104211110.580124112@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifsfs.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) --- 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 @@ out_destroy_decrypt_wq: 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");