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authorStefano Brivio <sbrivio@redhat.com>2022-01-26 06:45:31 +0100
committerStefano Brivio <sbrivio@redhat.com>2022-01-26 16:30:59 +0100
commitbe265eef0631217e6566781d388ae078c4797752 (patch)
treee2e53742621534c718c1995e9f519a2c401cb6cd
parent34872fadec608a6305ab9bcdd15592282cb194a5 (diff)
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tcp: Don't round down MSS to >= 64KiB page size, but clamp it in any case
On some architectures, the page size is bigger than the maximum size of an Ethernet frame. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
-rw-r--r--tcp.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/tcp.c b/tcp.c
index 18f07b6..36c2bb5 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1671,7 +1671,7 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
}
if (flags & SYN) {
- uint16_t mss;
+ int mss;
/* Options: MSS, NOP and window scale (8 bytes) */
optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
@@ -1691,10 +1691,10 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
if (c->low_wmem &&
!conn->local && !tcp_rtt_dst_low(conn))
mss = MIN(mss, PAGE_SIZE);
- else
+ else if (mss > PAGE_SIZE)
mss = ROUND_DOWN(mss, PAGE_SIZE);
}
- *(uint16_t *)data = htons(mss);
+ *(uint16_t *)data = htons(MIN(USHRT_MAX, mss));
data += OPT_MSS_LEN - 2;
th->doff += OPT_MSS_LEN / 4;