[PATCH] lib/string_helpers: rework overflow-dependent code

[Justin Stitt]

When @size is 0, the desired behavior is to allow unlimited bytes to be
parsed. Currently, this relies on some intentional arithmetic overflow
where --size gives us SIZE_MAX when size is 0.

Explicitly spell out the desired behavior without relying on intentional
overflow/underflow.

Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
 lib/string_helpers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 69ba49b853c7..4f887aa62fa0 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -321,6 +321,9 @@ int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
 {
 	char *out = dst;
 
+	if (!size)
+		size = SIZE_MAX;
+
 	while (*src && --size) {
 		if (src[0] == '\\' && src[1] != '\0' && size > 1) {
 			src++;

---
base-commit: ee9a43b7cfe2d8a3520335fea7d8ce71b8cabd9d
change-id: 20240808-b4-string_helpers_caa133-53effde85a18

Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>