From patchwork Sun Feb 4 02:17:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13544424 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85D2B749C; Sun, 4 Feb 2024 02:17:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707013065; cv=none; b=jfLvxtTpc6wWAPQCaFJHwQBPXlmgwHTynKLLVJHED+eo70cVw1n/fYZfJJhlRP/WOmqhvEvx5XXALi2DzZ4k3/REpawENCsp2/VyFCB8y/KyxfCapT+7Qov/oX1ATm5LYRDGpTBS+Fac1uCkSdM+ZIW+9db+5vSri6dGW+acatQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707013065; c=relaxed/simple; bh=gXEyVGfpVHTOGscWWhhgTHNWTU3KHsLHDUa7ooHXJ5o=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=KVOcfaACsb3SCUT9GSk7g9N7fyNSzlV7nHvR6f2ljwjj4yEuMvf2O3BQERIVmWf7AB+wFtF0NFJpQlaxesCZQgAFC+Iwb69e5NUCx3AR/3B6kwVIQhKzcQO+ZOKkflrx4J76RFh0Pr6weRRLj+PrxtSldHcsofpRvgA3qF6xbLk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=AZCOjPLC; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="AZCOjPLC" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=iVQFpkDCs9bj7WoZx+TN7eoBXzYpcdd2k1cx6KhK2YE=; b=AZCOjPLCvnzbtVNGM2vVDCasqK x2oOq7AbqjQtdx49CbQbf3ISp5j4Qjov/GCNC9krD+rtADL0gq4WJa6RtZDJnrwZi6CoszxXme8V1 9lsLsLsYd/Uyi09TVPGmavjzvmZ5f7wUu/Qdt4FRfjXBLGZ8cwe8MlBWDYdmBJ8v5xJM/hk8MNFrZ fTImNAv++iorzdLcnASa8Iu39QmdHty+M+wvWFHQXsib4yViHV/GrchrzNbLYduCYN/MGYg0C1KkA X7GIedptDhXNj+CL9F6y4Mf0WLhWdo3H1Zhoe2eTgE+VlqdZZfAX+PLi/NGJ95aBojiuNI2No5CYz beFWXBjw==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1rWS4j-004rDi-2X; Sun, 04 Feb 2024 02:17:41 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Christian Brauner , linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, Miklos Szeredi , linux-cifs@vger.kernel.org Subject: [PATCH 12/13] cifs_get_link(): bail out in unsafe case Date: Sun, 4 Feb 2024 02:17:38 +0000 Message-Id: <20240204021739.1157830-12-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240204021739.1157830-1-viro@zeniv.linux.org.uk> References: <20240204021436.GH2087318@ZenIV> <20240204021739.1157830-1-viro@zeniv.linux.org.uk> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: Al Viro ->d_revalidate() bails out there, anyway. It's not enough to prevent getting into ->get_link() in RCU mode, but that could happen only in a very contrieved setup. Not worth trying to do anything fancy here unless ->d_revalidate() stops kicking out of RCU mode at least in some cases. Signed-off-by: Al Viro --- fs/smb/client/cifsfs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c index e902de4e475a..630e74628dfe 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1172,6 +1172,9 @@ const char *cifs_get_link(struct dentry *dentry, struct inode *inode, { char *target_path; + if (!dentry) + return ERR_PTR(-ECHILD); + target_path = kmalloc(PATH_MAX, GFP_KERNEL); if (!target_path) return ERR_PTR(-ENOMEM);