@@ -190,7 +190,7 @@ static inline void le128_add(le128 *r, const le128 *v1, const le128 *v2)
r->b = cpu_to_le64(x + y);
r->a = cpu_to_le64(le64_to_cpu(v1->a) + le64_to_cpu(v2->a) +
- (x + y < x));
+ (add_would_overflow(x, y)));
}
/* Subtraction in Z/(2^{128}Z) */
@@ -251,7 +251,7 @@ crypto4xx_ctr_crypt(struct skcipher_request *req, bool encrypt)
* the whole IV is a counter. So fallback if the counter is going to
* overlow.
*/
- if (counter + nblks < counter) {
+ if (add_would_overflow(counter, nblks)) {
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->sw_cipher.cipher);
int ret;
In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded wrap-around addition test to use add_would_overflow(). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Aditya Srivastava <yashsri421@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: linux-crypto@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- crypto/adiantum.c | 2 +- drivers/crypto/amcc/crypto4xx_alg.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)