Fix a potential null-pointer dereference, and make the code a bit more
readable while doing so.
The NULL dereference could not be triggered, because the current code
never called format_hex_ex() with maxouput == 0 and separator == NULL.
But it's nicer to not depend on that.
Our use of int vs size_t for lengths needs some attention too, but I'm
not pulling that into this patch. Instead I decided to just make the
(previously existing) assumption that INT_MAX <= SIZE_MAX explicit by
adding a static_assert().
Signed-off-by: Steffan Karger <steffan.kar...@fox-it.com>
---
src/openvpn/buffer.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c
index 84d2669..6af8dbb 100644
--- a/src/openvpn/buffer.c
+++ b/src/openvpn/buffer.c
@@ -440,13 +440,16 @@ format_hex_ex (const uint8_t *data, int size, int
maxoutput,
unsigned int space_break_flags, const char* separator,
struct gc_arena *gc)
{
- struct buffer out = alloc_buf_gc (maxoutput ? maxoutput :
- ((size * 2) + (size / (space_break_flags &
FHE_SPACE_BREAK_MASK)) * (int) strlen (separator) + 2),
- gc);
- int i;
- for (i = 0; i < size; ++i)
+ const size_t bytes_per_hexblock = space_break_flags & FHE_SPACE_BREAK_MASK;
+ const size_t separator_len = separator ? strlen (separator) : 0;
+ static_assert (INT_MAX <= SIZE_MAX, "Code assumes INT_MAX <= SIZE_MAX");
+ const size_t out_len = maxoutput > 0 ? maxoutput :
+ ((size * 2) + ((size / bytes_per_hexblock) * separator_len) + 2);
+
+ struct buffer out = alloc_buf_gc (out_len, gc);
+ for (int i = 0; i < size; ++i)
{
- if (separator && i && !(i % (space_break_flags & FHE_SPACE_BREAK_MASK)))
+ if (separator && i && !(i % bytes_per_hexblock))
buf_printf (&out, "%s", separator);
if (space_break_flags & FHE_CAPS)
buf_printf (&out, "%02X", data[i]);
--
2.7.4
------------------------------------------------------------------------------
_______________________________________________
Openvpn-devel mailing list
Openvpn-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/openvpn-devel
