From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4214B335BAA; Mon, 18 Aug 2025 13:49:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524995; cv=none; b=hExZKIh/VGC64RUECFydgXZy1sNOEePTcWRg6LuOCDx406KXyiPGxa8sJ4UYUgCIe8IrCimes90W9MG05NbSbbpAIMk9l2ka9PDsQ5wcAMwlm840d6kYh6nZOsXqVqpdlKArI50yEYR8r2jeZd3glLUzVswIReHUJV508/heXBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524995; c=relaxed/simple; bh=Tm4QmAXvFvncvjpULh+l0xw/tCPNAomLIqn6E+E3jN0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qPtk/ZkGNnBrm7fbT9F5Pd9pGDM3i18Zxyxw2R7NW0Qm2YvFKZr5/R9pS+qetdnrU4qemUWV6e76ueSZxG6fn11cH6KKfRIjxUZot8cyfWHCmHM9cRARJvLrQc2zBm1ypSgPysClrTxFpxPd4+yCNrBu0r2QsFwxW9s+6m9bfuk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xn3w6//D; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xn3w6//D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A62C3C4CEEB; Mon, 18 Aug 2025 13:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755524995; bh=Tm4QmAXvFvncvjpULh+l0xw/tCPNAomLIqn6E+E3jN0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xn3w6//D+Osrvy6Ax9w/WP6zhX0cDD6+pQNRNHIidPnTgfwUb+bsEq1wJNhtWq2Nt viCGRs0CO2lTjkQNLX5TiioA7pcmsDycItz0WU+EVVQm0hpmcyBH+DMjen6C1mqwAD 4x+dNFAXUv1frVTyccs7RwwTmmTrz82q7pwrYM5k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, NeilBrown , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.16 099/570] smb/server: avoid deadlock when linking with ReplaceIfExists Date: Mon, 18 Aug 2025 14:41:26 +0200 Message-ID: <20250818124509.627769218@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124505.781598737@linuxfoundation.org> References: <20250818124505.781598737@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown [ Upstream commit d5fc1400a34b4ea5e8f2ce296ea12bf8c8421694 ] If smb2_create_link() is called with ReplaceIfExists set and the name does exist then a deadlock will happen. ksmbd_vfs_kern_path_locked() will return with success and the parent directory will be locked. ksmbd_vfs_remove_file() will then remove the file. ksmbd_vfs_link() will then be called while the parent is still locked. It will try to lock the same parent and will deadlock. This patch moves the ksmbd_vfs_kern_path_unlock() call to *before* ksmbd_vfs_link() and then simplifies the code, removing the file_present flag variable. Signed-off-by: NeilBrown Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/smb2pdu.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index a760785aa1ec..e5c469a87d64 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -6063,7 +6063,6 @@ static int smb2_create_link(struct ksmbd_work *work, { char *link_name = NULL, *target_name = NULL, *pathname = NULL; struct path path, parent_path; - bool file_present = false; int rc; if (buf_len < (u64)sizeof(struct smb2_file_link_info) + @@ -6096,11 +6095,8 @@ static int smb2_create_link(struct ksmbd_work *work, if (rc) { if (rc != -ENOENT) goto out; - } else - file_present = true; - - if (file_info->ReplaceIfExists) { - if (file_present) { + } else { + if (file_info->ReplaceIfExists) { rc = ksmbd_vfs_remove_file(work, &path); if (rc) { rc = -EINVAL; @@ -6108,21 +6104,17 @@ static int smb2_create_link(struct ksmbd_work *work, link_name); goto out; } - } - } else { - if (file_present) { + } else { rc = -EEXIST; ksmbd_debug(SMB, "link already exists\n"); goto out; } + ksmbd_vfs_kern_path_unlock(&parent_path, &path); } - rc = ksmbd_vfs_link(work, target_name, link_name); if (rc) rc = -EINVAL; out: - if (file_present) - ksmbd_vfs_kern_path_unlock(&parent_path, &path); if (!IS_ERR(link_name)) kfree(link_name); -- 2.39.5