Re: [PATCH RESEND 10/11] cifs: Add support for parsing WSL symlinks in version 1 format

[Pali Rohár]

On Monday 06 July 2026 20:48:18 Pali Rohár wrote:
> -	/* MS-FSCC 2.1.2.7 defines layout of the Target field only for Version 2. */
>  	u32 version = le32_to_cpu(buf->Version);
> +	switch (version) {
> +	case 1:
> +		/*
> +		 * Layout version 1 stores the symlink target in the data section of
> +		 * the file encoded in UTF-8 without trailing null-term byte.
> +		 */
>  
> -	if (version != 2) {
> +		oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, FILE_READ_DATA,
> +				     FILE_OPEN, CREATE_NOT_DIR | OPEN_REPARSE_POINT,
> +				     ACL_NO_MODE);
> +		oparms.fid = &fid;
> +		oplock = tcon->ses->server->oplocks ? REQ_OPLOCK : 0;
> +		rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, NULL);
> +		if (rc)
> +			goto out;
> +
> +		free_symname_utf8 = true;
> +		symname_utf8_len = le64_to_cpu(data->fi.EndOfFile);
> +		symname_utf8 = kmalloc(symname_utf8_len, GFP_KERNEL);
> +		if (!symname_utf8) {
> +			rc = -ENOMEM;
> +			goto out;
> +		}

Sashiko AI wrote:
https://sashiko.dev/#/patchset/20260706184819.22124-1-pali%40kernel.org

  Does this leak the server-side file handle and oplock?
  If this kmalloc() fails, the code jumps to the out label without calling
  tcon->ses->server->ops->close(xid, tcon, &fid).

This is really a problem. I would suggest to move the kmalloc() block
above the tcon->ses->server->ops->open(...) block which should address
this issue. E.g.:

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index 3418e4b66022..3fe57d166776 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -1133,6 +1133,14 @@ static int parse_reparse_wsl_symlink(struct reparse_wsl_symlink_data_buffer *buf
 		 * the file encoded in UTF-8 without trailing null-term byte.
 		 */

+		free_symname_utf8 = true;
+		symname_utf8_len = le64_to_cpu(data->fi.EndOfFile);
+		symname_utf8 = kmalloc(symname_utf8_len, GFP_KERNEL);
+		if (!symname_utf8) {
+			rc = -ENOMEM;
+			goto out;
+		}
+
 		oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, FILE_READ_DATA,
 				     FILE_OPEN, CREATE_NOT_DIR | OPEN_REPARSE_POINT,
 				     ACL_NO_MODE);
@@ -1142,14 +1150,6 @@ static int parse_reparse_wsl_symlink(struct reparse_wsl_symlink_data_buffer *buf
 		if (rc)
 			goto out;

-		free_symname_utf8 = true;
-		symname_utf8_len = le64_to_cpu(data->fi.EndOfFile);
-		symname_utf8 = kmalloc(symname_utf8_len, GFP_KERNEL);
-		if (!symname_utf8) {
-			rc = -ENOMEM;
-			goto out;
-		}
-
 		buf_type = CIFS_NO_BUFFER;
 		io_parms = (struct cifs_io_parms) {
 			.netfid = fid.netfid,