[PATCH] tools/nolibc/stdlib: fix getenv() with empty environment

[Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>]

The environ pointer itself is never NULL, this is guaranteed by crt.h.
However if the environment is empty, environ will point to a NULL
pointer.
While this case will be checked by the loop later, this only happens
after the first loop iteration.
To avoid reading invalid memory inside the loop, fix the test that
checks for an empty environment.

Fixes: 077d0a392446 ("tools/nolibc/stdlib: add a simple getenv() implementation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
---
 tools/include/nolibc/stdlib.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/include/nolibc/stdlib.h b/tools/include/nolibc/stdlib.h
index 75aa273c23a6153db6a32facaea16457a522703b..c31967378cf1f699283d801487c1a91d17e4d1ce 100644
--- a/tools/include/nolibc/stdlib.h
+++ b/tools/include/nolibc/stdlib.h
@@ -90,7 +90,7 @@ char *getenv(const char *name)
 {
 	int idx, i;
 
-	if (environ) {
+	if (*environ) {
 		for (idx = 0; environ[idx]; idx++) {
 			for (i = 0; name[i] && name[i] == environ[idx][i];)
 				i++;

---
base-commit: 2f87d0916ce0d2925cedbc9e8f5d6291ba2ac7b2
change-id: 20241016-nolibc-getenv-f99f4d3df2cd

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>