[PATCH 1/7] crypto: hisilicon/hpre - fix pointer dereference before length check

[Weili Qian]

In hpre_rsa_drop_leading_zeros(), the loop condition dereferences *ptr
before checking *len, causing an out-of-bounds read when *len is zero.

Swap to while (*len && !**ptr) to test length first.

Fixes: c8b4b477079d ("crypto: hisilicon - add HiSilicon HPRE accelerator")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Weili Qian <qianweili@xxxxxxxxxx>
---
 drivers/crypto/hisilicon/hpre/hpre_crypto.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/hisilicon/hpre/hpre_crypto.c b/drivers/crypto/hisilicon/hpre/hpre_crypto.c
index 09077abbf6ad..7894211b9972 100644
--- a/drivers/crypto/hisilicon/hpre/hpre_crypto.c
+++ b/drivers/crypto/hisilicon/hpre/hpre_crypto.c
@@ -720,7 +720,7 @@ static void hpre_dh_exit_tfm(struct crypto_kpp *tfm)
 
 static void hpre_rsa_drop_leading_zeros(const char **ptr, size_t *len)
 {
-	while (!**ptr && *len) {
+	while (*len && !**ptr) {
 		(*ptr)++;
 		(*len)--;
 	}
-- 
2.43.0