https://github.com/torvalds/linux
Revision a39d0d7bdf8c21ac7645c02e9676b5cb2b804c31 authored by Jean Delvare on 28 September 2020, 09:10:37 UTC, committed by Alex Deucher on 29 September 2020, 21:09:22 UTC
A recent attempt to fix a ref count leak in
amdgpu_display_crtc_set_config() turned out to be doing too much and
"fixed" an intended decrease as if it were a leak. Undo that part to
restore the proper balance. This is the very nature of this function
to increase or decrease the power reference count depending on the
situation.

Consequences of this bug is that the power reference would
eventually get down to 0 while the display was still in use,
resulting in that display switching off unexpectedly.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Fixes: e008fa6fb415 ("drm/amdgpu: fix ref count leak in amdgpu_display_crtc_set_config")
Cc: stable@vger.kernel.org
Cc: Navid Emamdoost <navid.emamdoost@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 parent c73d05e
Raw File
Tip revision: a39d0d7bdf8c21ac7645c02e9676b5cb2b804c31 authored by Jean Delvare on 28 September 2020, 09:10:37 UTC
drm/amdgpu: restore proper ref count in amdgpu_display_crtc_set_config
Tip revision: a39d0d7
nhpoly1305.c
// SPDX-License-Identifier: GPL-2.0
/*
 * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
 *
 * Copyright 2018 Google LLC
 */

/*
 * "NHPoly1305" is the main component of Adiantum hashing.
 * Specifically, it is the calculation
 *
 *	H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L)))
 *
 * from the procedure in section 6.4 of the Adiantum paper [1].  It is an
 * ε-almost-∆-universal (ε-∆U) hash function for equal-length inputs over
 * Z/(2^{128}Z), where the "∆" operation is addition.  It hashes 1024-byte
 * chunks of the input with the NH hash function [2], reducing the input length
 * by 32x.  The resulting NH digests are evaluated as a polynomial in
 * GF(2^{130}-5), like in the Poly1305 MAC [3].  Note that the polynomial
 * evaluation by itself would suffice to achieve the ε-∆U property; NH is used
 * for performance since it's over twice as fast as Poly1305.
 *
 * This is *not* a cryptographic hash function; do not use it as such!
 *
 * [1] Adiantum: length-preserving encryption for entry-level processors
 *     (https://eprint.iacr.org/2018/720.pdf)
 * [2] UMAC: Fast and Secure Message Authentication
 *     (https://fastcrypto.org/umac/umac_proc.pdf)
 * [3] The Poly1305-AES message-authentication code
 *     (https://cr.yp.to/mac/poly1305-20050329.pdf)
 */

#include <asm/unaligned.h>
#include <crypto/algapi.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/poly1305.h>
#include <crypto/nhpoly1305.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>

static void nh_generic(const u32 *key, const u8 *message, size_t message_len,
		       __le64 hash[NH_NUM_PASSES])
{
	u64 sums[4] = { 0, 0, 0, 0 };

	BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
	BUILD_BUG_ON(NH_NUM_PASSES != 4);

	while (message_len) {
		u32 m0 = get_unaligned_le32(message + 0);
		u32 m1 = get_unaligned_le32(message + 4);
		u32 m2 = get_unaligned_le32(message + 8);
		u32 m3 = get_unaligned_le32(message + 12);

		sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
		sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
		sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
		sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
		sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
		sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
		sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
		sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
		key += NH_MESSAGE_UNIT / sizeof(key[0]);
		message += NH_MESSAGE_UNIT;
		message_len -= NH_MESSAGE_UNIT;
	}

	hash[0] = cpu_to_le64(sums[0]);
	hash[1] = cpu_to_le64(sums[1]);
	hash[2] = cpu_to_le64(sums[2]);
	hash[3] = cpu_to_le64(sums[3]);
}

/* Pass the next NH hash value through Poly1305 */
static void process_nh_hash_value(struct nhpoly1305_state *state,
				  const struct nhpoly1305_key *key)
{
	BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0);

	poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash,
			     NH_HASH_BYTES / POLY1305_BLOCK_SIZE, 1);
}

/*
 * Feed the next portion of the source data, as a whole number of 16-byte
 * "NH message units", through NH and Poly1305.  Each NH hash is taken over
 * 1024 bytes, except possibly the final one which is taken over a multiple of
 * 16 bytes up to 1024.  Also, in the case where data is passed in misaligned
 * chunks, we combine partial hashes; the end result is the same either way.
 */
static void nhpoly1305_units(struct nhpoly1305_state *state,
			     const struct nhpoly1305_key *key,
			     const u8 *src, unsigned int srclen, nh_t nh_fn)
{
	do {
		unsigned int bytes;

		if (state->nh_remaining == 0) {
			/* Starting a new NH message */
			bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES);
			nh_fn(key->nh_key, src, bytes, state->nh_hash);
			state->nh_remaining = NH_MESSAGE_BYTES - bytes;
		} else {
			/* Continuing a previous NH message */
			__le64 tmp_hash[NH_NUM_PASSES];
			unsigned int pos;
			int i;

			pos = NH_MESSAGE_BYTES - state->nh_remaining;
			bytes = min(srclen, state->nh_remaining);
			nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash);
			for (i = 0; i < NH_NUM_PASSES; i++)
				le64_add_cpu(&state->nh_hash[i],
					     le64_to_cpu(tmp_hash[i]));
			state->nh_remaining -= bytes;
		}
		if (state->nh_remaining == 0)
			process_nh_hash_value(state, key);
		src += bytes;
		srclen -= bytes;
	} while (srclen);
}

int crypto_nhpoly1305_setkey(struct crypto_shash *tfm,
			     const u8 *key, unsigned int keylen)
{
	struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm);
	int i;

	if (keylen != NHPOLY1305_KEY_SIZE)
		return -EINVAL;

	poly1305_core_setkey(&ctx->poly_key, key);
	key += POLY1305_BLOCK_SIZE;

	for (i = 0; i < NH_KEY_WORDS; i++)
		ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32));

	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_setkey);

int crypto_nhpoly1305_init(struct shash_desc *desc)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);

	poly1305_core_init(&state->poly_state);
	state->buflen = 0;
	state->nh_remaining = 0;
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_init);

int crypto_nhpoly1305_update_helper(struct shash_desc *desc,
				    const u8 *src, unsigned int srclen,
				    nh_t nh_fn)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);
	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
	unsigned int bytes;

	if (state->buflen) {
		bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen);
		memcpy(&state->buffer[state->buflen], src, bytes);
		state->buflen += bytes;
		if (state->buflen < NH_MESSAGE_UNIT)
			return 0;
		nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
				 nh_fn);
		state->buflen = 0;
		src += bytes;
		srclen -= bytes;
	}

	if (srclen >= NH_MESSAGE_UNIT) {
		bytes = round_down(srclen, NH_MESSAGE_UNIT);
		nhpoly1305_units(state, key, src, bytes, nh_fn);
		src += bytes;
		srclen -= bytes;
	}

	if (srclen) {
		memcpy(state->buffer, src, srclen);
		state->buflen = srclen;
	}
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_update_helper);

int crypto_nhpoly1305_update(struct shash_desc *desc,
			     const u8 *src, unsigned int srclen)
{
	return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic);
}
EXPORT_SYMBOL(crypto_nhpoly1305_update);

int crypto_nhpoly1305_final_helper(struct shash_desc *desc, u8 *dst, nh_t nh_fn)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);
	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);

	if (state->buflen) {
		memset(&state->buffer[state->buflen], 0,
		       NH_MESSAGE_UNIT - state->buflen);
		nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
				 nh_fn);
	}

	if (state->nh_remaining)
		process_nh_hash_value(state, key);

	poly1305_core_emit(&state->poly_state, NULL, dst);
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_final_helper);

int crypto_nhpoly1305_final(struct shash_desc *desc, u8 *dst)
{
	return crypto_nhpoly1305_final_helper(desc, dst, nh_generic);
}
EXPORT_SYMBOL(crypto_nhpoly1305_final);

static struct shash_alg nhpoly1305_alg = {
	.base.cra_name		= "nhpoly1305",
	.base.cra_driver_name	= "nhpoly1305-generic",
	.base.cra_priority	= 100,
	.base.cra_ctxsize	= sizeof(struct nhpoly1305_key),
	.base.cra_module	= THIS_MODULE,
	.digestsize		= POLY1305_DIGEST_SIZE,
	.init			= crypto_nhpoly1305_init,
	.update			= crypto_nhpoly1305_update,
	.final			= crypto_nhpoly1305_final,
	.setkey			= crypto_nhpoly1305_setkey,
	.descsize		= sizeof(struct nhpoly1305_state),
};

static int __init nhpoly1305_mod_init(void)
{
	return crypto_register_shash(&nhpoly1305_alg);
}

static void __exit nhpoly1305_mod_exit(void)
{
	crypto_unregister_shash(&nhpoly1305_alg);
}

subsys_initcall(nhpoly1305_mod_init);
module_exit(nhpoly1305_mod_exit);

MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
MODULE_ALIAS_CRYPTO("nhpoly1305");
MODULE_ALIAS_CRYPTO("nhpoly1305-generic");
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