From 69cc1d0d7f3445d3671e05dcb7baabe7e36c5ed9 Mon Sep 17 00:00:00 2001
From: "Andrey A. Chernov" <ache@FreeBSD.org>
Date: Thu, 23 Aug 2001 07:42:40 +0000
Subject: [PATCH] Detect off_t EOVERFLOW of start/end offsets calculations for
 adv. lock, as POSIX require.

---
 sys/kern/kern_descrip.c | 17 +++++++++++++++--
 sys/kern/kern_lockf.c   | 13 ++++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index b72bf26e70b..78ac1a00d45 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -40,6 +40,7 @@
  */
 
 #include "opt_compat.h"
+#include <machine/limits.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/lock.h>
@@ -303,8 +304,14 @@ fcntl(p, uap)
 			fdrop(fp, p);
 			return (error);
 		}
-		if (fl.l_whence == SEEK_CUR)
+		if (fl.l_whence == SEEK_CUR) {
+			if ((fl.l_start > 0 &&
+			     fp->f_offset > OFF_MAX - fl.l_start) ||
+			    (fl.l_start < 0 &&
+			     fp->f_offset < OFF_MIN - fl.l_start))
+				return (EOVERFLOW);
 			fl.l_start += fp->f_offset;
+		}
 
 		switch (fl.l_type) {
 		case F_RDLCK:
@@ -356,8 +363,14 @@ fcntl(p, uap)
 			fdrop(fp, p);
 			return (EINVAL);
 		}
-		if (fl.l_whence == SEEK_CUR)
+		if (fl.l_whence == SEEK_CUR) {
+			if ((fl.l_start > 0 &&
+			     fp->f_offset > OFF_MAX - fl.l_start) ||
+			    (fl.l_start < 0 &&
+			     fp->f_offset < OFF_MIN - fl.l_start))
+				return (EOVERFLOW);
 			fl.l_start += fp->f_offset;
+		}
 		error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
 			    &fl, F_POSIX);
 		fdrop(fp, p);
diff --git a/sys/kern/kern_lockf.c b/sys/kern/kern_lockf.c
index ad3cb70051d..b93b541a882 100644
--- a/sys/kern/kern_lockf.c
+++ b/sys/kern/kern_lockf.c
@@ -39,6 +39,7 @@
 
 #include "opt_debug_lockf.h"
 
+#include <machine/limits.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
@@ -105,6 +106,8 @@ lf_advlock(ap, head, size)
 	off_t start, end;
 	int error;
 
+	if (fl->l_len < 0)
+		return (EINVAL);
 	/*
 	 * Convert the flock structure into a start and end.
 	 */
@@ -120,6 +123,9 @@ lf_advlock(ap, head, size)
 		break;
 
 	case SEEK_END:
+		/* size always >= 0 */
+		if (fl->l_start > 0 && size > OFF_MAX - fl->l_start)
+			return (EOVERFLOW);
 		start = size + fl->l_start;
 		break;
 
@@ -131,7 +137,12 @@ lf_advlock(ap, head, size)
 	if (fl->l_len == 0)
 		end = -1;
 	else {
-		end = start + fl->l_len - 1;
+		off_t oadd = fl->l_len - 1;
+
+		/* fl->l_len & start are non-negative */
+		if (oadd > OFF_MAX - start)
+			return (EOVERFLOW);
+		end = start + oadd;
 		if (end < start)
 			return (EINVAL);
 	}