git: de703e98e6c8 - stable/13 - Fix direct route installation with net/bird.

[Alexander V. Chernikov]

The branch stable/13 has been updated by melifaro:

URL: https://cgit.FreeBSD.org/src/commit/?id=de703e98e6c863874aa6012e3ce1a61eee58c846

commit de703e98e6c863874aa6012e3ce1a61eee58c846
Author:     Alexander V. Chernikov <melifaro at FreeBSD.org>
AuthorDate: 2021-04-10 15:25:24 +0000
Commit:     Alexander V. Chernikov <melifaro at FreeBSD.org>
CommitDate: 2021-04-19 18:52:57 +0000

    Fix direct route installation with net/bird.
    
    Slighly relax the gateway validation rules imposed by the
     2fe5a79425c7, by requiring only first 8 bytes (everyhing
     before sdl_data to be present in the AF_LINK gateway.
    
    Reported by:    olivier
    PR:             255089
    
    (cherry picked from commit 7f5f3fcc32bfa553faa007579dfcaed84be3b047)
---
 sys/net/rtsock.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index 12e485f917c8..c0996d318fb2 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -1381,20 +1381,21 @@ cleanup_xaddrs_gateway(struct rt_addrinfo *info)
 #endif
 	case AF_LINK:
 		{
-			struct sockaddr_dl_short *gw_sdl;
+			struct sockaddr_dl *gw_sdl;
 
-			gw_sdl = (struct sockaddr_dl_short *)gw;
-			if (gw_sdl->sdl_len < sizeof(struct sockaddr_dl_short)) {
+			size_t sdl_min_len = offsetof(struct sockaddr_dl, sdl_data);
+			gw_sdl = (struct sockaddr_dl *)gw;
+			if (gw_sdl->sdl_len < sdl_min_len) {
 				printf("gw sdl_len too small\n");
 				return (EINVAL);
 			}
 
 			const struct sockaddr_dl_short sdl = {
 				.sdl_family = AF_LINK,
-				.sdl_len = sizeof(struct sockaddr_dl_short),
+				.sdl_len = sdl_min_len,
 				.sdl_index = gw_sdl->sdl_index,
 			};
-			*gw_sdl = sdl;
+			memcpy(gw_sdl, &sdl, sdl_min_len);
 			break;
 		}
 	}