bootutil: Fix memory leak in HKDF implementation (73315f7b) · Commits · Wenxi XU / Mcuboot

The bootutil_hmac_sha256_set_key routine performs some dynamic memory allocations when mbedTLS is used. To properly free the allocated memory, bootutil_hmac_sha256_drop must be called before reinitializing the HMAC context using bootutil_hmac_sha256_init. However, in the hkdf routine, the HMAC context was freed only once even though it was initialized multiple times. Signed-off-by:

Thomas Altenbach <thomas.altenbach@legrand.com>

boot/bootutil/src/encrypted.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -276,6 +276,8 @@ hkdf(uint8_t ikm, uint16_t ikm_len, uint8_t info, uint16_t info_len,
		goto error;
		}

		bootutil_hmac_sha256_drop(&hmac);

		/*
		* Expand
		*/
		@@ -315,6 +317,8 @@ hkdf(uint8_t ikm, uint16_t ikm_len, uint8_t info, uint16_t info_len,
		goto error;
		}

		bootutil_hmac_sha256_drop(&hmac);

		if (len > BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE) {
		memcpy(&okm[off], T, BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE);
		len -= BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE;
		@@ -324,7 +328,6 @@ hkdf(uint8_t ikm, uint16_t ikm_len, uint8_t info, uint16_t info_len,
		}
		}

		bootutil_hmac_sha256_drop(&hmac);
		return 0;

		error:

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