patch 9.0.1969: [security] buffer-overflow in trunc_string()
Problem: buffer-overflow in trunc_string()
Solution: Add NULL at end of buffer
Currently trunc_string() assumes that when the string is too long,
buf[e-1] will always be writeable. But that assumption may not always be
true. The condition currently looks like this
else if (e + 3 < buflen)
[...]
else
{
// can't fit in the "...", just truncate it
buf[e - 1] = NUL;
}
but this means, we may run into the last else clause with e still being
larger than buflen. So a buffer overflow occurs.
So instead of using `buf[e - 1]`, let's just always
truncate at `buf[buflen - 1]` which should always be writable.
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/message.c b/src/message.c
index 2fc6cef..83c8b4f 100644
--- a/src/message.c
+++ b/src/message.c
@@ -353,7 +353,7 @@
else
{
// can't fit in the "...", just truncate it
- buf[e - 1] = NUL;
+ buf[buflen - 1] = NUL;
}
}