Re: [PATCH] net: ncsi: Adding padding bytes in the payload
From: Paul Menzel <hidden>
Date: 2021-10-12 08:04:26
Also in:
linux-aspeed, lkml, openbmc
Dear Kumar, Thank you for your patch. Nit: Could you please use the imperative mood in the commit message summary: > net: ncsi: Add padding bytes in the payload Or more descriptive: > net: ncsi: Padd payload to be 32-bit aligned to fix dropped packets Am 12.10.21 um 08:22 schrieb Kumar Thangavel:
Update NC-SI command handler (both standard and OEM) to take into account of payload paddings in allocating skb (in case of payload size is not 32-bit aligned). The checksum field follows payload field, without taking payload padding into account can cause checksum being truncated, leading to dropped packets.
How can this be reproduced?
quoted hunk ↗ jump to hunk
Signed-off-by: Kumar Thangavel <redacted> --- net/ncsi/ncsi-cmd.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c index ba9ae482141b..4625fc935603 100644 --- a/net/ncsi/ncsi-cmd.c +++ b/net/ncsi/ncsi-cmd.c@@ -214,11 +214,19 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb, struct ncsi_cmd_oem_pkt *cmd; unsigned int len; + /* NC-SI spec requires payload to be padded with 0
It’d be great, if you included the specification version, and section if the requirement.
+ * to 32-bit boundary before the checksum field. + * Ensure the padding bytes are accounted for in + * skb allocation + */ +
Please remove the blank line.
quoted hunk ↗ jump to hunk
+ unsigned short payload = ALIGN(nca->payload, 4); + len = sizeof(struct ncsi_cmd_pkt_hdr) + 4; - if (nca->payload < 26) + if (payload < 26) len += 26; else - len += nca->payload; + len += payload; cmd = skb_put_zero(skb, len); memcpy(&cmd->mfr_id, nca->data, nca->payload);@@ -272,6 +280,7 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca) struct net_device *dev = nd->dev; int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; + int payload; int len = hlen + tlen; struct sk_buff *skb; struct ncsi_request *nr;@@ -281,14 +290,18 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca) return NULL; /* NCSI command packet has 16-bytes header, payload, 4 bytes checksum. + * Payload needs padding so that the checksum field follwoing payload is
following
+ * aligned to 32bit boundary.
32-bit
* The packet needs padding if its payload is less than 26 bytes to * meet 64 bytes minimal ethernet frame length. */ len += sizeof(struct ncsi_cmd_pkt_hdr) + 4; - if (nca->payload < 26) + + payload = ALIGN(nca->payload, 4); + if (payload < 26) len += 26; else - len += nca->payload; + len += payload; /* Allocate skb */ skb = alloc_skb(len, GFP_ATOMIC);
Besides the nits, this looks fine to me. Kind regards, Paul