From: Mark Andrews <marka@isc.org>
Date: Wed, 8 Mar 2023 05:05:03 +0000 (+1100)
Subject: Silence NULL pointer dereferene false positive
X-Git-Tag: v9.19.12~29^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bf58c10dced30d34372fdfc4a778286370a4bfb8;p=thirdparty%2Fbind9.git

Silence NULL pointer dereferene false positive

Only attempt to digest 'in' if it is non NULL.  This will prevent
false positives about NULL pointer dereferences against 'in' and
should also speed up the processing.
---

diff --git a/lib/isc/siphash.c b/lib/isc/siphash.c
index 46bd5de70aa..ce24a6229f0 100644
--- a/lib/isc/siphash.c
+++ b/lib/isc/siphash.c
@@ -90,51 +90,52 @@ isc_siphash24(const uint8_t *k, const uint8_t *in, const size_t inlen,
 
 	uint64_t b = ((uint64_t)inlen) << 56;
 
-	const uint8_t *end = (in == NULL)
-				     ? NULL
-				     : in + inlen - (inlen % sizeof(uint64_t));
-	const size_t left = inlen & 7;
+	if (in != NULL && inlen != 0) {
+		const uint8_t *end = in + inlen - (inlen % sizeof(uint64_t));
+		const size_t left = inlen & 7;
 
-	for (; in != end; in += 8) {
-		uint64_t m = case_sensitive
-				     ? ISC_U8TO64_LE(in)
-				     : isc_ascii_tolower8(ISC_U8TO64_LE(in));
+		for (; in != end; in += 8) {
+			uint64_t m =
+				case_sensitive
+					? ISC_U8TO64_LE(in)
+					: isc_ascii_tolower8(ISC_U8TO64_LE(in));
 
-		v3 ^= m;
+			v3 ^= m;
 
-		for (size_t i = 0; i < cROUNDS; ++i) {
-			SIPROUND(v0, v1, v2, v3);
-		}
+			for (size_t i = 0; i < cROUNDS; ++i) {
+				SIPROUND(v0, v1, v2, v3);
+			}
 
-		v0 ^= m;
-	}
+			v0 ^= m;
+		}
 
-	switch (left) {
-	case 7:
-		b |= U8TO64_ONE(case_sensitive, in[6]) << 48;
-		FALLTHROUGH;
-	case 6:
-		b |= U8TO64_ONE(case_sensitive, in[5]) << 40;
-		FALLTHROUGH;
-	case 5:
-		b |= U8TO64_ONE(case_sensitive, in[4]) << 32;
-		FALLTHROUGH;
-	case 4:
-		b |= U8TO64_ONE(case_sensitive, in[3]) << 24;
-		FALLTHROUGH;
-	case 3:
-		b |= U8TO64_ONE(case_sensitive, in[2]) << 16;
-		FALLTHROUGH;
-	case 2:
-		b |= U8TO64_ONE(case_sensitive, in[1]) << 8;
-		FALLTHROUGH;
-	case 1:
-		b |= U8TO64_ONE(case_sensitive, in[0]);
-		FALLTHROUGH;
-	case 0:
-		break;
-	default:
-		UNREACHABLE();
+		switch (left) {
+		case 7:
+			b |= U8TO64_ONE(case_sensitive, in[6]) << 48;
+			FALLTHROUGH;
+		case 6:
+			b |= U8TO64_ONE(case_sensitive, in[5]) << 40;
+			FALLTHROUGH;
+		case 5:
+			b |= U8TO64_ONE(case_sensitive, in[4]) << 32;
+			FALLTHROUGH;
+		case 4:
+			b |= U8TO64_ONE(case_sensitive, in[3]) << 24;
+			FALLTHROUGH;
+		case 3:
+			b |= U8TO64_ONE(case_sensitive, in[2]) << 16;
+			FALLTHROUGH;
+		case 2:
+			b |= U8TO64_ONE(case_sensitive, in[1]) << 8;
+			FALLTHROUGH;
+		case 1:
+			b |= U8TO64_ONE(case_sensitive, in[0]);
+			FALLTHROUGH;
+		case 0:
+			break;
+		default:
+			UNREACHABLE();
+		}
 	}
 
 	v3 ^= b;
@@ -173,39 +174,40 @@ isc_halfsiphash24(const uint8_t *k, const uint8_t *in, const size_t inlen,
 
 	uint32_t b = ((uint32_t)inlen) << 24;
 
-	const uint8_t *end = (in == NULL)
-				     ? NULL
-				     : in + inlen - (inlen % sizeof(uint32_t));
-	const int left = inlen & 3;
+	if (in != NULL && inlen != 0) {
+		const uint8_t *end = in + inlen - (inlen % sizeof(uint32_t));
+		const int left = inlen & 3;
 
-	for (; in != end; in += 4) {
-		uint32_t m = case_sensitive
-				     ? ISC_U8TO32_LE(in)
-				     : isc_ascii_tolower4(ISC_U8TO32_LE(in));
+		for (; in != end; in += 4) {
+			uint32_t m =
+				case_sensitive
+					? ISC_U8TO32_LE(in)
+					: isc_ascii_tolower4(ISC_U8TO32_LE(in));
 
-		v3 ^= m;
+			v3 ^= m;
 
-		for (size_t i = 0; i < cROUNDS; ++i) {
-			HALFSIPROUND(v0, v1, v2, v3);
-		}
+			for (size_t i = 0; i < cROUNDS; ++i) {
+				HALFSIPROUND(v0, v1, v2, v3);
+			}
 
-		v0 ^= m;
-	}
+			v0 ^= m;
+		}
 
-	switch (left) {
-	case 3:
-		b |= U8TO32_ONE(case_sensitive, in[2]) << 16;
-		FALLTHROUGH;
-	case 2:
-		b |= U8TO32_ONE(case_sensitive, in[1]) << 8;
-		FALLTHROUGH;
-	case 1:
-		b |= U8TO32_ONE(case_sensitive, in[0]);
-		FALLTHROUGH;
-	case 0:
-		break;
-	default:
-		UNREACHABLE();
+		switch (left) {
+		case 3:
+			b |= U8TO32_ONE(case_sensitive, in[2]) << 16;
+			FALLTHROUGH;
+		case 2:
+			b |= U8TO32_ONE(case_sensitive, in[1]) << 8;
+			FALLTHROUGH;
+		case 1:
+			b |= U8TO32_ONE(case_sensitive, in[0]);
+			FALLTHROUGH;
+		case 0:
+			break;
+		default:
+			UNREACHABLE();
+		}
 	}
 
 	v3 ^= b;