From 4204b130b8a4d1cd2c4a0d9a5a09993e8948defe Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 2 Jan 2021 14:59:09 +0100 Subject: crypto: ecdh - avoid buffer overflow in ecdh_set_secret() Pavel reports that commit 8319c80ab523 ("crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()") fixes one problem but introduces another: the unconditional memcpy() introduced by that commit may overflow the target buffer if the source data is invalid, which could be the result of intentional tampering. So check params.key_size explicitly against the size of the target buffer before validating the key further. Fixes: 8319c80ab523 ("crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()") Reported-by: Pavel Machek Cc: Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- crypto/ecdh.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/crypto/ecdh.c b/crypto/ecdh.c index d56b8603..96f80c8f 100644 --- a/crypto/ecdh.c +++ b/crypto/ecdh.c @@ -39,7 +39,8 @@ static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf, struct ecdh params; unsigned int ndigits; - if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0) + if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0 || + params.key_size > sizeof(ctx->private_key)) return -EINVAL; ndigits = ecdh_supported_curve(params.curve_id); -- cgit v1.2.3