[PATCH v2] crypto: qat - use simple_strtoull to improve qat_uclo_parse_num

[Thorsten Blum <thorsten.blum@linux.dev>]

Replace the manual string copying and parsing logic with a call to
simple_strtoull() to simplify and improve qat_uclo_parse_num().

Ensure that the parsed number does not exceed UINT_MAX, and add an
approximate upper-bound check (no more than 19 digits) to guard against
overflow.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Use simple_strtoull(), return -EINVAL, and guard against overflow as
  suggested by Andy
- Link to v1: https://lore.kernel.org/lkml/20251022123622.349544-1-thorsten.blum@linux.dev/
---
 drivers/crypto/intel/qat/qat_common/qat_uclo.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/crypto/intel/qat/qat_common/qat_uclo.c b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
index 18c3e4416dc5..06d49cb781ae 100644
--- a/drivers/crypto/intel/qat/qat_common/qat_uclo.c
+++ b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
@@ -200,20 +200,12 @@ qat_uclo_cleanup_batch_init_list(struct icp_qat_fw_loader_handle *handle,
 
 static int qat_uclo_parse_num(char *str, unsigned int *num)
 {
-	char buf[16] = {0};
-	unsigned long ae = 0;
-	int i;
-
-	strscpy(buf, str, sizeof(buf));
-	for (i = 0; i < 16; i++) {
-		if (!isdigit(buf[i])) {
-			buf[i] = '\0';
-			break;
-		}
-	}
-	if ((kstrtoul(buf, 10, &ae)))
-		return -EFAULT;
+	unsigned long long ae;
+	char *end;
 
+	ae = simple_strtoull(str, &end, 10);
+	if (ae > UINT_MAX || str == end || (end - str) > 19)
+		return -EINVAL;
 	*num = (unsigned int)ae;
 	return 0;
 }
-- 
2.51.0