From: Steffan Karger Date: Mon, 28 Nov 2016 16:55:07 +0000 (+0100) Subject: Clean up format_hex_ex() X-Git-Tag: v2.3.14~5 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=384302478f967e4fbb5e4d813eb30a5c15d00a14;p=thirdparty%2Fopenvpn.git Clean up format_hex_ex() 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 Acked-by: Gert Doering Message-Id: <1480352107-19652-1-git-send-email-steffan.karger@fox-it.com> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13269.html Signed-off-by: Gert Doering --- diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c index fb3b52d17..edbdd666f 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 36819e0a8..4d7fef96e 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