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authorStefano Brivio <sbrivio@redhat.com>2022-05-20 10:36:11 +0200
committerStefano Brivio <sbrivio@redhat.com>2022-05-20 10:36:11 +0200
commitd27cc3e4355834a545581f4beafbfff9e0761914 (patch)
tree935e40c747e94df8d4a474ce334f9120c21250cf
parenta951e0b9efcbb64ca8b1d7c62c6c27a4498d21d6 (diff)
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tcp: Work around gcc 12 bogus warning in tcp_rtt_dst_check()
gcc 12.1.x (e.g. current OpenSUSE Tumbleweed, x86_64 only, gcc-12-1.4.x86_64) reports: tcp.c: In function ‘tcp_send_flag’: tcp.c:1014:9: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=] 1014 | memcpy(low_rtt_dst + hole++, &conn->a.a6, sizeof(conn->a.a6)); | ^ tcp.c:559:24: note: at offset -16 into destination object ‘low_rtt_dst’ of size 128 559 | static struct in6_addr low_rtt_dst[LOW_RTT_TABLE_SIZE]; | but 'hole' can't be -1, because the low_rtt_dst table is guaranteed to have a hole: if we happened to write to the last entry, we'll go back to index 0 and clear that one. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
-rw-r--r--tcp.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/tcp.c b/tcp.c
index e68409a..53af3db 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1011,6 +1011,12 @@ static void tcp_rtt_dst_check(const struct tcp_conn *conn,
hole = i;
}
+ /* Keep gcc 12 happy: this won't actually happen because the table is
+ * guaranteed to have a hole, see the second memcpy() below.
+ */
+ if (hole == -1)
+ return;
+
memcpy(low_rtt_dst + hole++, &conn->a.a6, sizeof(conn->a.a6));
if (hole == LOW_RTT_TABLE_SIZE)
hole = 0;