vfs: fs_context: fix up param length parsing in legacy_parse_param

commit 722d948 upstream. The "PAGE_SIZE - 2 - size" calculation in legacy_parse_param() is an unsigned type so a large value of "size" results in a high positive value instead of a negative value as expected. Fix this by getting rid of the subtraction. Signed-off-by: Jamie Hill-Daniel <[email protected]> Signed-off-by: William Liu <[email protected]> Tested-by: Salvatore Bonaccorso <[email protected]> Tested-by: Thadeu Lima de Souza Cascardo <[email protected]> Acked-by: Dan Carpenter <[email protected]> Acked-by: Al Viro <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
omnirom · Jan 20, 2022 · bd2aed0 · bd2aed0
1 parent c2f067d
commit bd2aed0
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/fs_context.c b/fs/fs_context.c
@@ -585,7 +585,7 @@ static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param)
 			      param->key);
 	}
 
-	if (len > PAGE_SIZE - 2 - size)
+	if (size + len + 2 > PAGE_SIZE)
 		return invalf(fc, "VFS: Legacy: Cumulative options too large");
 	if (strchr(param->key, ',') ||
 	    (param->type == fs_value_is_string &&