mount.cifs can pass a device with multiple delimiters in it. This will
cause rename(2) to fail with ENOENT.
V2:
- Make sanitize_path more readable.
- Fix multiple delimiters between UNC and prepath.
- Avoid a memory leak if a bad user starts putting a lot of delimiters
in the path on purpose.
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2031200
Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Cc: stable@xxxxxxxxxxxxxxx # 5.11+
Signed-off-by: Thiago Rafael Becker <trbecker@xxxxxxxxx>
---
fs/cifs/fs_context.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 6a179ae753c1..e3ed25dc6f3f 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -434,6 +434,42 @@ int smb3_parse_opt(const char *options, const char *key, char **val)
return rc;
}
+/*
+ * Remove duplicate path delimiters. Windows is supposed to do that
+ * but there are some bugs that prevent rename from working if there are
+ * multiple delimiters.
+ *
+ * Returns a sanitized duplicate of @path. The caller is responsible for
+ * cleaning up the original.
+ */
+#define IS_DELIM(c) ((c) == '/' || (c) == '\\')
+static char *sanitize_path(char *path)
+{
+ char *cursor1 = path, *cursor2 = path;
+
+ /* skip all prepended delimiters */
+ while (IS_DELIM(*cursor1))
+ cursor1++;
+
+ /* copy the first letter */
+ *cursor2 = *cursor1;
+
+ /* copy the remainder... */
+ while (*(cursor1++)) {
+ /* ... skipping all duplicated delimiters */
+ if (IS_DELIM(*cursor1) && IS_DELIM(*cursor2))
+ continue;
+ *(++cursor2) = *cursor1;
+ }
+
+ /* if the last character is a delimiter, skip it */
+ if (IS_DELIM(*(cursor2 - 1)))
+ cursor2--;
+
+ *(cursor2) = '\0';
+ return kstrdup(path, GFP_KERNEL);
+}
+
/*
* Parse a devname into substrings and populate the ctx->UNC and ctx->prepath
* fields with the result. Returns 0 on success and an error otherwise
@@ -493,7 +529,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
if (!*pos)
return 0;
- ctx->prepath = kstrdup(pos, GFP_KERNEL);
+ ctx->prepath = sanitize_path(pos);
if (!ctx->prepath)
return -ENOMEM;
--
2.31.1
