#22387: bgmac (Broadcom 47xx) "oversized packet" kernel panic
---------------------+--------------------------------
Reporter: cds@… | Owner: developers
Type: defect | Status: new
Priority: normal | Milestone:
Component: kernel | Version: Chaos Calmer 15.05
Resolution: | Keywords:
---------------------+--------------------------------
Comment (by cds@…):
I tried booting with the following kernel patch:
{{{
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -467,19 +467,24 @@ static int bgmac_dma_rx_read(struct bgma
break;
}
+ /* Omit CRC. */
+ len -= ETH_FCS_LEN;
+
+ /* Add in the alignment offsets. */
+ len += BGMAC_RX_FRAME_OFFSET +
BGMAC_RX_BUF_OFFSET;
+
+ /* Check for packets that are too large for the
skb. */
if (len > BGMAC_RX_ALLOC_SIZE) {
- bgmac_err(bgmac, "Found oversized packet
at slot %d, DMA issue!\n",
- ring->start);
+ bgmac_err(bgmac, "Found oversized (%d)
packet at slot %d, DMA issue!\n",
+ len, ring->start);
put_page(virt_to_head_page(buf));
break;
}
- /* Omit CRC. */
- len -= ETH_FCS_LEN;
-
+ /* Build the skb with the len, which has been
verified
+ * above, and pull up to the alignment offset. */
skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
- skb_put(skb, BGMAC_RX_FRAME_OFFSET +
- BGMAC_RX_BUF_OFFSET + len);
+ skb_put(skb, len);
skb_pull(skb, BGMAC_RX_FRAME_OFFSET +
BGMAC_RX_BUF_OFFSET);
}}}
This corrects the arithmetic in bgmac near the site of the panic bug.
Unfortunately, it does *nothing* to improve the symptoms. Something else
is going on here and I'm not sure what.
--
Ticket URL: <https://dev.openwrt.org/ticket/22387#comment:2>
OpenWrt <http://openwrt.org>
Opensource Wireless Router Technology
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