git: 8ca1b9dc9369 - main - devel/gdb: Avoid a divide by zero in kgdb.

From: John Baldwin <jhb_at_FreeBSD.org>
Date: Thu, 14 Oct 2021 22:22:07 UTC 
The branch main has been updated by jhb (doc, src committer):

URL: https://cgit.FreeBSD.org/ports/commit/?id=8ca1b9dc93695b2288f6b40d08c392b5a6dfbef2

commit 8ca1b9dc93695b2288f6b40d08c392b5a6dfbef2
Author:     John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2021-10-14 22:21:45 +0000
Commit:     John Baldwin <jhb@FreeBSD.org>
CommitDate: 2021-10-14 22:21:45 +0000

    devel/gdb: Avoid a divide by zero in kgdb.
    
    Don't divide by zero if the message buffer size in a crashdump is
    zero.
    
    Reported by:    glebius
    Reviewed by:    pizzamig (maintainer), emaste
    Sponsored by:   Netflix
    Differential Revision:  https://reviews.freebsd.org/D32486
---
 devel/gdb/Makefile              | 1 +
 devel/gdb/files/kgdb/fbsd-kvm.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/devel/gdb/Makefile b/devel/gdb/Makefile
index 010dd16305bc..66abc21d8070 100644
--- a/devel/gdb/Makefile
+++ b/devel/gdb/Makefile
@@ -2,6 +2,7 @@
 
 PORTNAME=	gdb
 DISTVERSION=	11.1
+PORTREVISION=	1
 CATEGORIES=	devel
 MASTER_SITES=	GNU
 
diff --git a/devel/gdb/files/kgdb/fbsd-kvm.c b/devel/gdb/files/kgdb/fbsd-kvm.c
index 4f11f641f78f..78fa9d331a5b 100644
--- a/devel/gdb/files/kgdb/fbsd-kvm.c
+++ b/devel/gdb/files/kgdb/fbsd-kvm.c
@@ -144,6 +144,8 @@ kgdb_dmesg(void)
 	} catch (const gdb_exception_error &e) {
 		return;
 	}
+	if (size == 0)
+		return;
 	rseq = MSGBUF_SEQ_TO_POS(size, rseq);
 	wseq = MSGBUF_SEQ_TO_POS(size, wseq);
 	if (rseq == wseq)