net/netlink: fix NETLINK_LIST_MEMBERSHIPS length report

The current code for the length calculation wrongly truncates the reported length of the groups array, causing an under report of the subscribed groups. To fix this, use 'BITS_TO_BYTES()' which rounds up the division by 8. Fixes: b42be38 ("netlink: add API to retrieve all group memberships") Signed-off-by: Pedro Tammela <[email protected]> Reviewed-by: Simon Horman <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
1054009064 · May 31, 2023 · f4e4534 · f4e4534
1 parent 36eec02
commit f4e4534
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
@@ -1779,7 +1779,7 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
 				break;
 			}
 		}
-		if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
+		if (put_user(ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)), optlen))
 			err = -EFAULT;
 		netlink_unlock_table();
 		return err;