Cherry-pick of commit 29404010 from master, slightly reworked to match the
2.3 codebase (no flags inside space_break here), and pulled in the new
static_assert() fallback we also have in master now.
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 | 10 +++++++---
src/openvpn/error.h | 8 ++++++++
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c
index fb3b52d..edbdd66 100644
--- a/src/openvpn/buffer.c
+++ b/src/openvpn/buffer.c
@@ -400,9 +400,13 @@ format_hex_ex (const uint8_t *data, int size, int
maxoutput,
int space_break, const char* separator,
struct gc_arena *gc)
{
- struct buffer out = alloc_buf_gc (maxoutput ? maxoutput :
- ((size * 2) + (size / space_break) * (int)
strlen (separator) + 2),
- gc);
+ 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 / space_break) * separator_len) + 2);
+
+ struct buffer out = alloc_buf_gc (out_len, gc);
+
int i;
for (i = 0; i < size; ++i)
{
diff --git a/src/openvpn/error.h b/src/openvpn/error.h
index 36819e0..4d7fef9 100644
--- a/src/openvpn/error.h
+++ b/src/openvpn/error.h
@@ -217,6 +217,14 @@ FILE *msg_fp(const unsigned int flags);
void assert_failed (const char *filename, int line, const char *condition)
__attribute__((__noreturn__));
+/* Poor-man's static_assert() for when not supplied by assert.h, taken from
+ * Linux's sys/cdefs.h under GPLv2 */
+#ifndef static_assert
+#define static_assert(expr, diagnostic) \
+ extern int (*__OpenVPN_static_assert_function (void)) \
+ [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
+#endif
+
#ifdef ENABLE_DEBUG
void crash (void); /* force a segfault (debugging only) */
#endif
--
2.7.4
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