With current OpenSUSE Tumbleweed on aarch64 (gcc-12-1.3.aarch64) and on x86_64 (gcc-12-1.4.x86_64), but curiously not on armv7hl (gcc-12-1.3.armv7hl), gcc warns about using the _pointer_ to the 802.3 header to write the whole frame to the tap descriptor: reading between 62 and 4294967357 bytes from a region of size 14 which is bogus: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483 Probably declaring udp_sock_fill_data_v{4,6}() as noinline would "fix" this, but that's on the data path, so I'd rather not. Use a gcc pragma instead. Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com> --- v2: LLVM 13.0.1 doesn't know about -Wstringop-overread, and clang-tidy warns about the unknown diagnostic pragma: make it conditional v3: gcc < 11 doesn't know about it either, but it doesn't implement __has_warning udp.c | 4 ++++ util.h | 23 +++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/udp.c b/udp.c index f425d14..98e3eaa 100644 --- a/udp.c +++ b/udp.c @@ -714,8 +714,10 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n, b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh)); if (c->mode == MODE_PASTA) { + PRAGMA_STRINGOP_OVERREAD_IGNORE if (write(c->fd_tap, &b->eh, sizeof(b->eh) + ip_len) < 0) debug("tap write: %s", strerror(errno)); + PRAGMA_STRINGOP_OVERREAD_IGNORE_POP pcap((char *)&b->eh, sizeof(b->eh) + ip_len); return; @@ -813,8 +815,10 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n, b->ip6h.hop_limit = 255; if (c->mode == MODE_PASTA) { + PRAGMA_STRINGOP_OVERREAD_IGNORE if (write(c->fd_tap, &b->eh, sizeof(b->eh) + ip_len) < 0) debug("tap write: %s", strerror(errno)); + PRAGMA_STRINGOP_OVERREAD_IGNORE_POP pcap((char *)&b->eh, sizeof(b->eh) + ip_len); return; diff --git a/util.h b/util.h index f85a87a..6f2c702 100644 --- a/util.h +++ b/util.h @@ -102,6 +102,29 @@ enum { (void *)(arg)); \ } while (0) + +#ifdef __has_warning +# if __has_warning("-Wstringop-overread") +# define PRAGMA_STRINGOP_OVERREAD_IGNORE \ + _Pragma("GCC diagnostic ignored \"-Wstringop-overread\"") +# define PRAGMA_STRINGOP_OVERREAD_IGNORE_POP \ + _Pragma("GCC diagnostic pop") +# else +# define PRAGMA_STRINGOP_OVERREAD_IGNORE +# define PRAGMA_STRINGOP_OVERREAD_IGNORE_POP +# endif +#else +# if defined(__GNUC__) && __GNUC__ >= 11 +# define PRAGMA_STRINGOP_OVERREAD_IGNORE \ + _Pragma("GCC diagnostic ignored \"-Wstringop-overread\"") +# define PRAGMA_STRINGOP_OVERREAD_IGNORE_POP \ + _Pragma("GCC diagnostic pop") +# else +# define PRAGMA_STRINGOP_OVERREAD_IGNORE +# define PRAGMA_STRINGOP_OVERREAD_IGNORE_POP +# endif +#endif + #if __BYTE_ORDER == __BIG_ENDIAN #define L2_BUF_ETH_IP4_INIT \ { \ -- 2.35.1