[PATCH net-next v4] keys, dns: Drop unused NUL terminator from upayload->data

upayload->data includes an extra NUL terminator even though it is never
used as a C string. In-tree users access only the first
upayload->datalen bytes.

Remove the redundant NUL terminator and allocate one byte less for
upayload->data in dns_resolver_preparse().

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v4:
- Drop patch 2/2 from the series and submit 1/2 as a standalone patch
- Reword subject and patch description
- v3: https://lore.kernel.org/r/20260427114422.313356-3-thorsten.blum@linux.dev/ (local)

Changes in v3:
- Update commit message
- v2: https://lore.kernel.org/r/20260409225703.158552-4-thorsten.blum@linux.dev/ (local)

Changes in v2:
- No changes in patch 1/2
- v1: https://lore.kernel.org/r/20260406175810.1018681-3-thorsten.blum@linux.dev/ (local)
---
 net/dns_resolver/dns_key.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
index c3c8c3240ef9..451247864a63 100644
--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c

@@ -203,7 +203,7 @@ dns_resolver_preparse(struct key_preparsed_payload *prep)
 	kdebug("store result");
 	prep->quotalen = result_len;
 
-	upayload = kmalloc_flex(*upayload, data, result_len + 1);
+	upayload = kmalloc_flex(*upayload, data, result_len);
 	if (!upayload) {
 		kleave(" = -ENOMEM");
 		return -ENOMEM;

@@ -211,7 +211,6 @@ dns_resolver_preparse(struct key_preparsed_payload *prep)
 
 	upayload->datalen = result_len;
 	memcpy(upayload->data, data, result_len);
-	upayload->data[result_len] = '\0';
 
 	prep->payload.data[dns_key_data] = upayload;
 	kleave(" = 0");