Fix a signedness mistake in secp256k1_num_set_hex

sipa · sipa · commit fa492f059db6 · 2014-08-27T01:21:57.000+02:00
We were using a potentially signed char as index in an array.
diff --git a/src/num_gmp_impl.h b/src/num_gmp_impl.h
@@ -300,7 +300,7 @@ void static secp256k1_num_set_hex(secp256k1_num_t *r, const char *a, int alen) {
     };
     unsigned char num[257] = {};
     for (int i=0; i<alen; i++) {
-        num[i] = cvt[a[i]];
+        num[i] = cvt[(unsigned char)a[i]];
     }
     r->limbs = mpn_set_str(r->data, num, alen, 16);
     while (r->limbs > 1 && r->data[r->limbs-1] == 0) r->limbs--;

Original file line number	Diff line number	Diff line change
`@@ -300,7 +300,7 @@ void static secp256k1_num_set_hex(secp256k1_num_t r, const char a, int alen) {`
`300`	`300`	`};`
`301`	`301`	`unsigned char num[257] = {};`
`302`	`302`	`for (int i=0; i<alen; i++) {`
`303`		`- num[i] = cvt[a[i]];`
	`303`	`+ num[i] = cvt[(unsigned char)a[i]];`
`304`	`304`	`}`
`305`	`305`	`r->limbs = mpn_set_str(r->data, num, alen, 16);`
`306`	`306`	`while (r->limbs > 1 && r->data[r->limbs-1] == 0) r->limbs--;`