From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794314658; b=BWzUp14KZd+4DnYFFWg77YJpAyMRPRs5YDdzHjBDYIABM8TesP4IOZZLr0nLqlzbrCk8 2OeraVLZMCi7cO4cir7GUExH4CpRQHlvy0uBEl2RXjJw2api83a/X3pqlDcAU/rbf4Bs+ W/0z/My2YxilXXxPfX3AyDyOu+DtclreVPRzBvV2bovEQaf9FPIDsbeCFQfKEqs+oyvWY 8+NEDsKI6N8oL7Fs8uyddyHaMsFwH+jVYXGsgsU4zgQ+Ck95Qlx6bz7yF9NLl6LGK4LPA FxXQNIXn1AKsoSF5N4tenr9xxMQOFygeAiiKq2tJKAAwAJB6KHkNpQMgnWMtgG/ihmA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794314658; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=rUQdxBhN+AW/V9J408tsmx6ctX2hwymu4P11z5XJCtQ=; b=Gz0E1XJbGGzcBT2oiny+SbhYtj4XiwTJsfLGLkHzcPS+mPp+ZShzu2K8DgOhIIwa8if8 otUl2WoXotyo69YUlqzVaQ6at2YE8a1PIzpzzMrsJaUengbrxHrKu3MYjkO1uF6BiYfqN Bkl0OrOGBxU1/kz9HPX9y17bBsq2GYpy7FT564lXZev3jkdhS84pre1tSB78ShU0nJ6zj P7mqT7YrRL64KZuwYquw0xakf0lQppVrCedOmMpiOqWDic81OVerZNor5j0dX9ajORckl T2vCqSDTkqbu5kIhWkYkyHehn2f4hJgC3DWh+t/sP7kDzLZ5UMYmxAkZwoF7umjQXFg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gAEr8PmK; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BE91606A31C for ; Tue, 10 Nov 2026 12:44:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gAEr8PmK Received: by smtp.kernel.org (Postfix) with ESMTPSA id 380F91F0089F; Tue, 10 Nov 2026 12:44:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794314657; bh=rUQdxBhN+AW/V9J408tsmx6ctX2hwymu4P11z5XJCtQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gAEr8PmKStKcu2Ya6jf/WMe3Np3QKoOTXkhZJt2nfeW+XWGw146PNdw8BPG4MDDgW zeklRjlqL2vrGO1zVnio7Z7qMC33iJXnVcIfrjMO7yot2tLBUHkuJuDPm5VKZSaqUo 2ceHd3ipmcTYHPCdfssRpKdWgxVauFLSm9eDWa34dq4j41f80bMXPzqWG5iwHtCcZe YN9zMFTRFwYjRnUcY4UkT9qvdszGFNt/dRW1DJrAMeJVI/slXpYWwk91/6M09xefIu OFjezm254A2PgT3bm1tNhojSA7DTmulidTDEyJ7rIiEf0KCt/fTTdtkglyurU/rN/E SgChbpSSruhYw== From: Sasha Levin To: stable@vger.kernel.org Cc: Daehyeon Ko <4ncienth@gmail.com>, Herbert Xu , Sasha Levin Subject: [PATCH 6.6.y] crypto: algif_skcipher - rewind rounded output bytes Date: Tue, 10 Nov 2026 07:44:16 -0500 Message-ID: <20261110124351.1434294-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107053242-failed-6.6-2f90facc7b94@kernel.org> References: <20261107053242-failed-6.6-2f90facc7b94@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Daehyeon Ko <4ncienth@gmail.com> [ Upstream commit 2f90facc7b94934653eb7ebfadcc25d503b89196 ] af_alg_get_rsgl() advances the receive iterator by the unrounded RX scatterlist length. For a continuing skcipher request, _skcipher_recvmsg() then rounds its local length down to a whole chunksize without restoring the iterator. A later chunk starts after bytes which the provider never wrote, while the syscall returns only the processed length. When copy_splice_read() supplies non-zeroed pages and publishes that return as a dense prefix, the gap exposes stale bytes from a previous page lifetime. With unprivileged xts(aes), a 31-byte MSG_MORE request followed by one final byte advances a 47-byte destination while returning 32 bytes. A hardened v7.2-rc5 image retained all 15 seeded stale bytes in 4,829 of 4,829 records. With init_on_alloc enabled, all 72,345 gap bytes observed were zero. Rewind the iterator by the tail excluded during rounding, before rejecting a zero processed length. The crypto request uses only the rounded length; af_alg_free_resources() releases the entire RX list before another receive iteration. The fixed target-like kernel returned byte-identical dense 48-byte output in 4,771 of 4,771 rounds. The unmodified kernel returned the vulnerable 32-byte short record in 2,409 of 2,409 rounds. Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Daehyeon Ko <4ncienth@gmail.com> Signed-off-by: Herbert Xu [ sashal: Adjusted patch context for the absent CRYPTO_SKCIPHER_REQ_NOTFINAL flag statement. ] Signed-off-by: Sasha Levin --- crypto/algif_skcipher.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 8729ef268d9d8..4fc077f31aa48 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -83,12 +83,15 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, * full block size buffers. */ if (ctx->more || len < ctx->used) { - if (len < bs) { + size_t excess = len % bs; + + len -= excess; + iov_iter_revert(&msg->msg_iter, excess); + + if (!len) { err = -EINVAL; goto free; } - - len -= len % bs; } /* -- 2.53.0