git: dae64402b3e8 - main - rtsock: fix panic in rtsock_msg_buffer()

The branch main has been updated by glebius:

URL: https://cgit.FreeBSD.org/src/commit/?id=dae64402b3e8ef7488db0df8003361f242573905

commit dae64402b3e8ef7488db0df8003361f242573905
Author:     Gleb Smirnoff <glebius@FreeBSD.org>
AuthorDate: 2024-11-18 22:12:42 +0000
Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2024-11-18 22:12:42 +0000

    rtsock: fix panic in rtsock_msg_buffer()
    
    The rtsock_msg_buffer() can be called without walkarg, just to calculate
    required length.  It can also be called with a degenerate walkarg, that
    doesn't have a w_req.  The latter happens when the function is called from
    update_rtm_from_info() for the second time.
    
    Zero init walkarg in update_rtm_from_info() and don't pass random stack
    garbage as w_req.
    
    In rtsock_msg_buffer() initialize compat32 boolean only once and take of
    possible empty w_req.  Simplify the rest of code once compat32 is already
    set.
    
    Reviewed by:            melifaro
    Differential Revision:  https://reviews.freebsd.org/D47662
    Reported-by: syzbot+d4a2682059e23179e76e@syzkaller.appspotmail.com
    Reported-by: syzbot+66d7c9b3062e27a56f3f@syzkaller.appspotmail.com
---
 sys/net/rtsock.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index 09d463dc17af..a5395dcf1469 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -921,8 +921,10 @@ update_rtm_from_info(struct rt_addrinfo *info, struct rt_msghdr **prtm,
 		 */
 	}
 
-	w.w_tmem = (caddr_t)rtm;
-	w.w_tmemsize = alloc_len;
+	w = (struct walkarg ){
+		.w_tmem = (caddr_t)rtm,
+		.w_tmemsize = alloc_len,
+	};
 	rtsock_msg_buffer(rtm->rtm_type, info, &w, &len);
 	rtm->rtm_addrs = info->rti_addrs;
 
@@ -1774,7 +1776,10 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int *
 	struct sockaddr_in6 *sin6;
 #endif
 #ifdef COMPAT_FREEBSD32
-	bool compat32 = false;
+	bool compat32;
+
+	compat32 = w != NULL && w->w_req != NULL &&
+	    (w->w_req->flags & SCTL_MASK32);
 #endif
 
 	switch (type) {
@@ -1782,10 +1787,9 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int *
 	case RTM_NEWADDR:
 		if (w != NULL && w->w_op == NET_RT_IFLISTL) {
 #ifdef COMPAT_FREEBSD32
-			if (w->w_req->flags & SCTL_MASK32) {
+			if (compat32)
 				len = sizeof(struct ifa_msghdrl32);
-				compat32 = true;
-			} else
+			else
 #endif
 				len = sizeof(struct ifa_msghdrl);
 		} else
@@ -1793,20 +1797,21 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int *
 		break;
 
 	case RTM_IFINFO:
+		if (w != NULL && w->w_op == NET_RT_IFLISTL) {
 #ifdef COMPAT_FREEBSD32
-		if (w != NULL && w->w_req->flags & SCTL_MASK32) {
-			if (w->w_op == NET_RT_IFLISTL)
+			if (compat32)
 				len = sizeof(struct if_msghdrl32);
 			else
+#endif
+				len = sizeof(struct if_msghdrl);
+		} else {
+#ifdef COMPAT_FREEBSD32
+			if (compat32)
 				len = sizeof(struct if_msghdr32);
-			compat32 = true;
-			break;
-		}
+			else
 #endif
-		if (w != NULL && w->w_op == NET_RT_IFLISTL)
-			len = sizeof(struct if_msghdrl);
-		else
-			len = sizeof(struct if_msghdr);
+				len = sizeof(struct if_msghdr);
+		}
 		break;
 
 	case RTM_NEWMADDR: