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
---
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