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 955D9350D61; Tue, 26 Aug 2025 13:48:23 +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=1756216103; cv=none; b=Bz7JaFVu9Bf1k2l/1ERMfTmV9jlit9zOg4fQMvgKlRyHj8cQKZ2pMLTprTb9Zm852If3Kd5U8PHeu6Xvi8kFZT5etDrYPSL4PXrLv2O/3iI8vDDbT460D0dF6cVHrF/c6mdRJDHNe91iGzMvsrE6doMh6hRCLV0YkELU1b7frU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756216103; c=relaxed/simple; bh=lCMTqazBoeNqF5A10hN5yc0X3I5HvWdiQ2ZJdPtAUX0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=V7OycddKmhSVqMzddhCL1d/9Ewc487THD9E6rmxp4t7YSrnuhAbaNPCkRKCPUWWDuUTDvabwalIr5u85a2TzMIwxDYJTgFTzZnn4Ud7oXnhmpql3xhQItJZX27PXat6fmNPz7EhbGfWC7dBUMktyVmwhhVlAVTV6AZWS0WF0zL8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=z5d4s6p4; 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="z5d4s6p4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD8CFC113CF; Tue, 26 Aug 2025 13:48:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756216103; bh=lCMTqazBoeNqF5A10hN5yc0X3I5HvWdiQ2ZJdPtAUX0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z5d4s6p4zQDbP8tMHnkIy7BedSOPv0tIiZ07pdTHPKD2zDNbnMv1GdO3+W7dc97qy TIRZBV18FihlzeJW/s8qmhSsuQK24Rn+AOZ3T2FosKAcRkPcqJocJHl/choSnfoDOz Mo6nj1yJtTV1SSYj5vbW1nIyh1Af2hI3ze+6GESk= 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 5.15 285/644] smb/server: avoid deadlock when linking with ReplaceIfExists Date: Tue, 26 Aug 2025 13:06:16 +0200 Message-ID: <20250826110953.443128971@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110946.507083938@linuxfoundation.org> References: <20250826110946.507083938@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 5.15-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/ksmbd/smb2pdu.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 76334a983cd2..3439dbad9389 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -5612,7 +5612,6 @@ 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) + @@ -5645,11 +5644,8 @@ 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; @@ -5657,21 +5653,17 @@ 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