patch 9.0.1899: potential buffer overflow in PBYTE macro
Problem: potential buffer overflow in PBYTE macro
Solution: Check returned memline length
closes: #13083
the PBYTE macro is used to put byte c at a position lp of the returned
memline. However, in case of unexpected errors ml_get_buf() may return
either "???" or an empty line in which case it is quite likely that we
are causing a buffer overrun.
Therefore, switch the macro PBYTE (which is only used in ops.c anyhow)
to a function, that verifies that we will only try to access within the
given length of the buffer.
Also, since the macro is only used in ops.c, move the definition from
macros.h to ops.c
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/ops.c b/src/ops.c
index f4524d3..aa6f4af 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -17,6 +17,9 @@
static void shift_block(oparg_T *oap, int amount);
static void mb_adjust_opend(oparg_T *oap);
static int do_addsub(int op_type, pos_T *pos, int length, linenr_T Prenum1);
+static void pbyte(pos_T lp, int c);
+#define PBYTE(lp, c) pbyte(lp, c)
+
// Flags for third item in "opchars".
#define OPF_LINES 1 // operator always works on lines
@@ -4349,3 +4352,18 @@
restore_lbr(lbr_saved);
#endif
}
+
+// put byte 'c' at position 'lp', but
+// verify, that the position to place
+// is actually safe
+ static void
+pbyte(pos_T lp, int c)
+{
+ char_u *p = ml_get_buf(curbuf, lp.lnum, TRUE);
+ int len = curbuf->b_ml.ml_line_len;
+
+ // safety check
+ if (lp.col >= len)
+ lp.col = (len > 1 ? len - 2 : 0);
+ *(p + lp.col) = c;
+}