--- b/usr.bin/patch/common.h	
+++ b/usr.bin/patch/common.h	
@@ -40,6 +40,7 @@ 
 #define	INITHUNKMAX 125		/* initial dynamic allocation size */
 #define	INITLINELEN 4096
 #define	BUFFERSIZE 4096
+#define	LINENUM_MAX LONG_MAX
 
 #define	SCCSPREFIX "s."
 #define	GET "get -e %s"
--- b/usr.bin/patch/pch.c	
+++ b/usr.bin/patch/pch.c	
@@ -501,6 +501,7 @@ another_hunk(void)
 	long	repl_backtrack_position;	/* file pos of first repl line */
 	LINENUM	repl_patch_line;		/* input line number for same */
 	LINENUM	ptrn_copiable;			/* # of copiable lines in ptrn */
+	const char *p_err;
 	char	*s;
 	size_t	len;
 	int	context = 0;
@@ -589,7 +590,10 @@ another_hunk(void)
 					malformed();
 				if (strnEQ(s, "0,0", 3))
 					memmove(s, s + 2, strlen(s + 2) + 1);
-				p_first = (LINENUM) atol(s);
+				p_first = (LINENUM) strtonum(s, 0, LINENUM_MAX, &p_err);
+				if (p_err != NULL)
+					fatal("at line %ld: bad line number %s",
+						p_input_line, s);
 				while (isdigit((unsigned char)*s))
 					s++;
 				if (*s == ',') {
@@ -597,7 +601,11 @@ another_hunk(void)
 						;
 					if (!*s)
 						malformed();
-					p_ptrn_lines = ((LINENUM) atol(s)) - p_first + 1;
+					p_ptrn_lines = ((LINENUM) strtonum(s, 0, 
+						LINENUM_MAX, &p_err)) - p_first + 1;
+					if (p_err != NULL)
+						fatal("at line %ld: bad line number %s",
+							p_input_line, s);
 				} else if (p_first)
 					p_ptrn_lines = 1;
 				else {
@@ -605,6 +613,9 @@ another_hunk(void)
 					p_first = 1;
 				}
 
+				if (p_first >= LINENUM_MAX - p_ptrn_lines ||
+					p_ptrn_lines >= LINENUM_MAX - 6)
+					malformed();
 				/* we need this much at least */
 				p_max = p_ptrn_lines + 6;
 				while (p_max >= hunkmax)
@@ -656,7 +667,10 @@ another_hunk(void)
 						;
 					if (!*s)
 						malformed();
-					p_newfirst = (LINENUM) atol(s);
+					p_newfirst = (LINENUM) strtonum(s, 0, LINENUM_MAX, &p_err);
+					if (p_err != NULL)
+						fatal("at line %ld: bad line number %s",
+							p_input_line, s);
 					while (isdigit((unsigned char)*s))
 						s++;
 					if (*s == ',') {
@@ -664,14 +678,21 @@ another_hunk(void)
 							;
 						if (!*s)
 							malformed();
-						p_repl_lines = ((LINENUM) atol(s)) -
-						    p_newfirst + 1;
+						p_repl_lines = ((LINENUM) strtonum(s, 0, 
+							LINENUM_MAX, &p_err)) - p_newfirst + 1;
+						if (p_err != NULL)
+								fatal("at line %ld: bad line number %s", 
+									p_input_line, s);
 					} else if (p_newfirst)
 						p_repl_lines = 1;
 					else {
 						p_repl_lines = 0;
 						p_newfirst = 1;
 					}
+
+					if (p_newfirst >= LINENUM_MAX - p_repl_lines ||
+						p_repl_lines >= LINENUM_MAX - p_end)
+						malformed();
 					p_max = p_repl_lines + p_end;
 					if (p_max > MAXHUNKSIZE)
 						fatal("hunk too large (%ld lines) at line %ld: %s",
@@ -864,11 +885,18 @@ hunk_done:
 		s = buf + 4;
 		if (!*s)
 			malformed();
-		p_first = (LINENUM) atol(s);
+		p_first = (LINENUM) strtonum(s, 0, LINENUM_MAX, &p_err);
+		if (p_err != NULL)
+				fatal("at line %ld: bad line number %s",
+					p_input_line, s);
 		while (isdigit((unsigned char)*s))
 			s++;
 		if (*s == ',') {
-			p_ptrn_lines = (LINENUM) atol(++s);
+			p_ptrn_lines = (LINENUM) strtonum(++s, 0, LINENUM_MAX,
+				&p_err);
+			if (p_err != NULL)
+				fatal("at line %ld: bad line number %s",
+					p_input_line, s);
 			while (isdigit((unsigned char)*s))
 				s++;
 		} else
@@ -877,11 +905,17 @@ hunk_done:
 			s++;
 		if (*s != '+' || !*++s)
 			malformed();
-		p_newfirst = (LINENUM) atol(s);
+		p_newfirst = (LINENUM) strtonum(s, 0, LINENUM_MAX, &p_err);
+		if (p_err != NULL)
+			fatal("at line %ld: bad line number %s",
+				p_input_line, s);
 		while (isdigit((unsigned char)*s))
 			s++;
 		if (*s == ',') {
-			p_repl_lines = (LINENUM) atol(++s);
+			p_repl_lines = (LINENUM) strtonum(++s, 0, LINENUM_MAX, &p_err);
+			if (p_err != NULL)
+				fatal("at line %ld: bad line number %s",
+					p_input_line, s);
 			while (isdigit((unsigned char)*s))
 				s++;
 		} else
@@ -890,6 +924,10 @@ hunk_done:
 			s++;
 		if (*s != '@')
 			malformed();
+		if (p_first >= LINENUM_MAX - p_ptrn_lines ||
+			p_newfirst > LINENUM_MAX - p_repl_lines ||
+			p_ptrn_lines >= LINENUM_MAX - p_repl_lines - 1)
+			malformed();
 		if (!p_ptrn_lines)
 			p_first++;	/* do append rather than insert */
 		p_max = p_ptrn_lines + p_repl_lines + 1;
@@ -1029,35 +1067,52 @@ hunk_done:
 			next_intuit_at(line_beginning, p_input_line);
 			return false;
 		}
-		p_first = (LINENUM) atol(buf);
+		p_first = (LINENUM) strtonum(buf, 0, LINENUM_MAX, &p_err);
+		if (p_err != NULL)
+			fatal("at line %ld: bad line number %s",
+				p_input_line, buf);
 		for (s = buf; isdigit((unsigned char)*s); s++)
 			;
 		if (*s == ',') {
-			p_ptrn_lines = (LINENUM) atol(++s) - p_first + 1;
+			p_ptrn_lines = (LINENUM) strtonum(++s, 0,
+				LINENUM_MAX, &p_err) - p_first + 1;
+			if (p_err != NULL)
+				malformed(); 
 			while (isdigit((unsigned char)*s))
 				s++;
 		} else
 			p_ptrn_lines = (*s != 'a');
+		if (p_first >= LINENUM_MAX - p_ptrn_lines)
+			malformed();
 		hunk_type = *s;
 		if (hunk_type == 'a')
 			p_first++;	/* do append rather than insert */
-		min = (LINENUM) atol(++s);
+		min = (LINENUM) strtonum(++s, 0, LINENUM_MAX, &p_err);
+		if (p_err != NULL)
+			malformed();
 		for (; isdigit((unsigned char)*s); s++)
 			;
-		if (*s == ',')
-			max = (LINENUM) atol(++s);
-		else
+		if (*s == ',') {
+			max = (LINENUM) strtonum(++s, 0, LINENUM_MAX, &p_err);
+			if (p_err != NULL)
+				malformed();
+		} else
 			max = min;
+		if (min < 0 || min > max || max - min == LINENUM_MAX)
+			malformed();
 		if (hunk_type == 'd')
 			min++;
-		p_end = p_ptrn_lines + 1 + max - min + 1;
+		p_newfirst = min;
+		p_repl_lines = max - min + 1;
+		if (p_newfirst > LINENUM_MAX - p_repl_lines ||
+			p_ptrn_lines >= LINENUM_MAX - p_repl_lines - 1)
+			malformed();
+		p_end = p_ptrn_lines + p_repl_lines + 1;
 		if (p_end > MAXHUNKSIZE)
 			fatal("hunk too large (%ld lines) at line %ld: %s",
 			    p_end, p_input_line, buf);
 		while (p_end >= hunkmax)
 			grow_hunkmax();
-		p_newfirst = min;
-		p_repl_lines = max - min + 1;
 		snprintf(buf, buf_size, "*** %ld,%ld\n", p_first,
 		    p_first + p_ptrn_lines - 1);
 		p_line[0] = savestr(buf);