From 573169dd88ac5ca0cf75d09464dddba398e83011 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Mon, 13 Jan 2020 23:17:16 -0500
Subject: acme: fix buffer overflow introduced in parsetag refactor

---
 src/cmd/acme/fns.h  |  2 +-
 src/cmd/acme/look.c |  2 +-
 src/cmd/acme/wind.c | 12 ++++++------
 3 files changed, 8 insertions(+), 8 deletions(-)

(limited to 'src/cmd/acme')

diff --git a/src/cmd/acme/fns.h b/src/cmd/acme/fns.h
index fece1dbd..c0339c23 100644
--- a/src/cmd/acme/fns.h
+++ b/src/cmd/acme/fns.h
@@ -95,7 +95,7 @@ void		flushwarnings(void);
 void		startplumbing(void);
 long	nlcount(Text*, long, long, long*);
 long	nlcounttopos(Text*, long, long, long);
-Rune*	parsetag(Window*, int*);
+Rune*	parsetag(Window*, int, int*);
 
 Runestr	runestr(Rune*, uint);
 Range range(int, int);
diff --git a/src/cmd/acme/look.c b/src/cmd/acme/look.c
index bde8b2c9..35667c6c 100644
--- a/src/cmd/acme/look.c
+++ b/src/cmd/acme/look.c
@@ -490,7 +490,7 @@ dirname(Text *t, Rune *r, int n)
 		goto Rescue;
 	if(n>=1 && r[0]=='/')
 		goto Rescue;
-	b = parsetag(t->w, &i);
+	b = parsetag(t->w, n, &i);
 	slash = -1;
 	for(i--; i >= 0; i--){
 		if(b[i] == '/'){
diff --git a/src/cmd/acme/wind.c b/src/cmd/acme/wind.c
index 2782dbc7..0cba5920 100644
--- a/src/cmd/acme/wind.c
+++ b/src/cmd/acme/wind.c
@@ -113,7 +113,7 @@ delrunepos(Window *w)
 	Rune *r;
 	int i;
 
-	r = parsetag(w, &i);
+	r = parsetag(w, 0, &i);
 	free(r);
 	i += 2;
 	if(i >= w->tag.file->b.nc)
@@ -416,7 +416,7 @@ wincleartag(Window *w)
 
 	/* w must be committed */
 	n = w->tag.file->b.nc;
-	r = parsetag(w, &i);
+	r = parsetag(w, 0, &i);
 	for(; i<n; i++)
 		if(r[i] == '|')
 			break;
@@ -434,7 +434,7 @@ wincleartag(Window *w)
 }
 
 Rune*
-parsetag(Window *w, int *len)
+parsetag(Window *w, int extra, int *len)
 {
 	static Rune Ldelsnarf[] = { ' ', 'D', 'e', 'l', ' ', 'S', 'n', 'a', 'r', 'f', 0 };
 	static Rune Lspacepipe[] = { ' ', '|', 0 };
@@ -442,7 +442,7 @@ parsetag(Window *w, int *len)
 	int i;
 	Rune *r, *p, *pipe;
 
-	r = runemalloc(w->tag.file->b.nc+1);
+	r = runemalloc(w->tag.file->b.nc+extra+1);
 	bufread(&w->tag.file->b, 0, r, w->tag.file->b.nc);
 	r[w->tag.file->b.nc] = '\0';
 
@@ -483,7 +483,7 @@ winsettag1(Window *w)
 	/* there are races that get us here with stuff in the tag cache, so we take extra care to sync it */
 	if(w->tag.ncache!=0 || w->tag.file->mod)
 		wincommit(w, &w->tag);	/* check file name; also guarantees we can modify tag contents */
-	old = parsetag(w, &i);
+	old = parsetag(w, 0, &i);
 	if(runeeq(old, i, w->body.file->name, w->body.file->nname) == FALSE){
 		textdelete(&w->tag, 0, i, TRUE);
 		textinsert(&w->tag, 0, w->body.file->name, w->body.file->nname, TRUE);
@@ -604,7 +604,7 @@ wincommit(Window *w, Text *t)
 			textcommit(f->text[i], FALSE);	/* no-op for t */
 	if(t->what == Body)
 		return;
-	r = parsetag(w, &i);
+	r = parsetag(w, 0, &i);
 	if(runeeq(r, i, w->body.file->name, w->body.file->nname) == FALSE){
 		seq++;
 		filemark(w->body.file);
-- 
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