hw/net/dp8393x: fix integer underflow in dp8393x_do_transmit_packets()
An integer underflow could occur during packet transmission due to 'tx_len' not
being updated if SONIC_TFC register is set to zero. Check for negative 'tx_len'
when removing existing FCS.
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1899722
Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-id: 20201124092445.658647-1-mcascell@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
index 674b04b..205c0de 100644
--- a/hw/net/dp8393x.c
+++ b/hw/net/dp8393x.c
@@ -495,6 +495,10 @@
} else {
/* Remove existing FCS */
tx_len -= 4;
+ if (tx_len < 0) {
+ SONIC_ERROR("tx_len is %d\n", tx_len);
+ break;
+ }
}
if (s->regs[SONIC_RCR] & (SONIC_RCR_LB1 | SONIC_RCR_LB0)) {
