From: Arnd Bergmann <arnd@arndb.de>
Date: Fri, 11 Aug 2023 15:46:33 +0200
Subject: crypto: drivers - avoid memcpy size warning
Patch-mainline: v6.6-rc1
Git-commit: f9fc1ec28baeeef6259127b3cbeb34986834574f
References: jsc#PED-6831
Some configurations with gcc-12 or gcc-13 produce a warning for the source
and destination of a memcpy() in atmel_sha_hmac_compute_ipad_hash() potentially
overlapping:
In file included from include/linux/string.h:254,
from drivers/crypto/atmel-sha.c:15:
drivers/crypto/atmel-sha.c: In function 'atmel_sha_hmac_compute_ipad_hash':
include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing 129 or more bytes at offsets 408 and 280 overlaps 1 or more bytes at offset 408 [-Werror=restrict]
57 | #define __underlying_memcpy __builtin_memcpy
| ^
include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy'
648 | __underlying_##op(p, q, __fortify_size); \
| ^~~~~~~~~~~~~
include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk'
693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
| ^~~~~~~~~~~~~~~~~~~~
drivers/crypto/atmel-sha.c:1773:9: note: in expansion of macro 'memcpy'
1773 | memcpy(hmac->opad, hmac->ipad, bs);
| ^~~~~~
The same thing happens in two more drivers that have the same logic:
drivers/crypto/chelsio/chcr_algo.c: In function 'chcr_ahash_setkey':
include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing 129 or more bytes at offsets 260 and 132 overlaps 1 or more bytes at offset 260 [-Werror=restrict]
drivers/crypto/bcm/cipher.c: In function 'ahash_hmac_setkey':
include/linux/fortify-string.h:57:33: error: '__builtin_memcpy' accessing between 129 and 4294967295 bytes at offsets 840 and 712 overlaps between 1 and 4294967167 bytes at offset 840 [-Werror=restrict]
I don't think it can actually happen because the size is strictly bounded
to the available block sizes, at most 128 bytes, though inlining decisions
could lead gcc to not see that.
Use the unsafe_memcpy() helper instead of memcpy(), with the only difference
being that this skips the hardening checks that produce the warning.
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/crypto/atmel-sha.c | 3 ++-
drivers/crypto/bcm/cipher.c | 3 ++-
drivers/crypto/chelsio/chcr_algo.c | 3 ++-
3 files changed, 6 insertions(+), 3 deletions(-)
--- a/drivers/crypto/atmel-sha.c
+++ b/drivers/crypto/atmel-sha.c
@@ -1770,7 +1770,8 @@ static int atmel_sha_hmac_compute_ipad_h
size_t bs = ctx->block_size;
size_t i, num_words = bs / sizeof(u32);
- memcpy(hmac->opad, hmac->ipad, bs);
+ unsafe_memcpy(hmac->opad, hmac->ipad, bs,
+ "fortified memcpy causes -Wrestrict warning");
for (i = 0; i < num_words; ++i) {
hmac->ipad[i] ^= 0x36363636;
hmac->opad[i] ^= 0x5c5c5c5c;
--- a/drivers/crypto/bcm/cipher.c
+++ b/drivers/crypto/bcm/cipher.c
@@ -2397,7 +2397,8 @@ static int ahash_hmac_setkey(struct cryp
memset(ctx->ipad + ctx->authkeylen, 0,
blocksize - ctx->authkeylen);
ctx->authkeylen = 0;
- memcpy(ctx->opad, ctx->ipad, blocksize);
+ unsafe_memcpy(ctx->opad, ctx->ipad, blocksize,
+ "fortified memcpy causes -Wrestrict warning");
for (index = 0; index < blocksize; index++) {
ctx->ipad[index] ^= HMAC_IPAD_VALUE;
--- a/drivers/crypto/chelsio/chcr_algo.c
+++ b/drivers/crypto/chelsio/chcr_algo.c
@@ -2216,7 +2216,8 @@ static int chcr_ahash_setkey(struct cryp
memcpy(hmacctx->ipad, key, keylen);
}
memset(hmacctx->ipad + keylen, 0, bs - keylen);
- memcpy(hmacctx->opad, hmacctx->ipad, bs);
+ unsafe_memcpy(hmacctx->opad, hmacctx->ipad, bs,
+ "fortified memcpy causes -Wrestrict warning");
for (i = 0; i < bs / sizeof(int); i++) {
*((unsigned int *)(&hmacctx->ipad) + i) ^= IPAD_DATA;