[dev] [PATCH] Simplify tdeletechar and tinsertblank and fix memory corruption.

From: noname <noname_AT_inventati.org>
Date: Wed, 23 Apr 2014 02:08:13 +0400

Current CSI parsing code uses strtol to parse arguments and allows them
to be negative. Negative argument is not properly handled in tdeletechar
and tinsertblank and results in memory corruption in memmove.

Reproduce with printf '\e[-500_AT_'

Patch also removes special handling for corner case and simplifies
the code.

Removed
        term.dirty[term.c.y] = 1
because tclearregion sets dirty flag.

---
 st.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)
diff --git a/st.c b/st.c
index 019f53c..ae76731 100644
--- a/st.c
+++ b/st.c
_AT_@ -1592,16 +1592,13 @@ tclearregion(int x1, int y1, int x2, int y2) {
 
 void
 tdeletechar(int n) {
-	int src = term.c.x + n;
-	int dst = term.c.x;
-	int size = term.col - src;
+	int dst, src, size;
 
-	term.dirty[term.c.y] = 1;
+	LIMIT(n, 0, term.col - term.c.x);
 
-	if(src >= term.col) {
-		tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
-		return;
-	}
+	dst = term.c.x;
+	src = term.c.x + n;
+	size = term.col - src;
 
 	memmove(&term.line[term.c.y][dst], &term.line[term.c.y][src],
 			size * sizeof(Glyph));
_AT_@ -1610,16 +1607,13 @@ tdeletechar(int n) {
 
 void
 tinsertblank(int n) {
-	int src = term.c.x;
-	int dst = src + n;
-	int size = term.col - dst;
+	int dst, src, size;
 
-	term.dirty[term.c.y] = 1;
+	LIMIT(n, 0, term.col - term.c.x);
 
-	if(dst >= term.col) {
-		tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
-		return;
-	}
+	dst = term.c.x + n;
+	src = term.c.x;
+	size = term.col - dst;
 
 	memmove(&term.line[term.c.y][dst], &term.line[term.c.y][src],
 			size * sizeof(Glyph));
-- 
1.8.4

Received on Wed Apr 23 2014 - 00:08:13 CEST