[v1] tmpfs: Unsigned expression compared with zero

Commit Message

guanjing Nov. 20, 2024, 10:51 a.m. UTC

The return value from the call to utf8_parse_version() is not
of the unsigned type.

However, the return value is being assigned to an unsigned int
variable 'version'. This will result in the inability to handle
errors that occur when parsing a UTF-8 version number from
a string.

Additionally, this patch can help eliminate the following
Coccicheck warning:

mm/shmem.c:4378:6-13: WARNING: Unsigned expression compared with zero: version < 0

Fixes: 58e55efd6c72 ("tmpfs: Add casefold lookup support")
Signed-off-by: guanjing <[e-mail]>
---
 fs/unicode/utf8-core.c  | 9 +++++----
 include/linux/unicode.h | 2 +-
 mm/shmem.c              | 5 +++--
 3 files changed, 9 insertions(+), 7 deletions(-)

Comments

André Almeida Nov. 20, 2024, 11:10 a.m. UTC | #1

Hi guanjing,

Em 20/11/2024 07:51, guanjing escreveu:
> The return value from the call to utf8_parse_version() is not
> of the unsigned type.
> 
> However, the return value is being assigned to an unsigned int
> variable 'version'. This will result in the inability to handle
> errors that occur when parsing a UTF-8 version number from
> a string.
> 
> Additionally, this patch can help eliminate the following
> Coccicheck warning:
> 
> mm/shmem.c:4378:6-13: WARNING: Unsigned expression compared with zero: version < 0
> 
> Fixes: 58e55efd6c72 ("tmpfs: Add casefold lookup support")
> Signed-off-by: guanjing <[e-mail]>

Another fix was already sent: 
https://lore.kernel.org/lkml/[e-mail]/

Patch

diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index 6fc9ab8667e6..c54dc7ac5ce6 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -219,9 +219,9 @@  EXPORT_SYMBOL(utf8_unload);
  *
  * @version: input string
  *
- * Returns the parsed version on success, negative code on error
+ * Returns 0 on success, negative code on error
  */
-int utf8_parse_version(char *version)
+int utf8_parse_version(char *version_str, unsigned int *version)
 {
 	substring_t args[3];
 	unsigned int maj, min, rev;
@@ -230,13 +230,14 @@  int utf8_parse_version(char *version)
 		{0, NULL}
 	};
 
-	if (match_token(version, token, args) != 1)
+	if (match_token(version_str, token, args) != 1)
 		return -EINVAL;
 
 	if (match_int(&args[0], &maj) || match_int(&args[1], &min) ||
 	    match_int(&args[2], &rev))
 		return -EINVAL;
 
-	return UNICODE_AGE(maj, min, rev);
+	*version = UNICODE_AGE(maj, min, rev);
+	return 0;
 }
 EXPORT_SYMBOL(utf8_parse_version);
diff --git a/include/linux/unicode.h b/include/linux/unicode.h
index 5e6b212a2aed..7de545bc66cb 100644
--- a/include/linux/unicode.h
+++ b/include/linux/unicode.h
@@ -78,6 +78,6 @@  int utf8_casefold_hash(const struct unicode_map *um, const void *salt,
 struct unicode_map *utf8_load(unsigned int version);
 void utf8_unload(struct unicode_map *um);
 
-int utf8_parse_version(char *version);
+int utf8_parse_version(char *version_str, unsigned int *version);
 
 #endif /* _LINUX_UNICODE_H */
diff --git a/mm/shmem.c b/mm/shmem.c
index ccb9629a0f70..7d07f649a8df 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4368,14 +4368,15 @@  static int shmem_parse_opt_casefold(struct fs_context *fc, struct fs_parameter *
 	unsigned int version = UTF8_LATEST;
 	struct unicode_map *encoding;
 	char *version_str = param->string + 5;
+	int ret;
 
 	if (!latest_version) {
 		if (strncmp(param->string, "utf8-", 5))
 			return invalfc(fc, "Only UTF-8 encodings are supported "
 				       "in the format: utf8-<version number>");
 
-		version = utf8_parse_version(version_str);
-		if (version < 0)
+		ret = utf8_parse_version(version_str, &version);
+		if (ret < 0)
 			return invalfc(fc, "Invalid UTF-8 version: %s", version_str);
 	}