[PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[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.

Fixes: fb4ee67529ff ("net/ncsi: Add NCSI OEM command support")
Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
Acked-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>

---
  v7:
   - Updated padding_bytes as const static int variable

  v6:
   - Updated type of padding_bytes variable
   - Updated type of payload
   - Seperated variable declarations and code

  v5:
   - Added Fixes tag
   - Added const variable for padding_bytes

  v4:
   - Used existing macro for max function

  v3:
   - Added Macro for MAX
   - Fixed the missed semicolon

  v2:
   - Added NC-SI spec version and section
   - Removed blank line
   - corrected spellings

  v1:
   - Initial draft

---
---
 net/ncsi/ncsi-cmd.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
index ba9ae482141b..9a6f10f4833e 100644
--- a/net/ncsi/ncsi-cmd.c
+++ b/net/ncsi/ncsi-cmd.c
@@ -18,6 +18,8 @@
 #include "internal.h"
 #include "ncsi-pkt.h"
 
+const static int padding_bytes = 26;
+
 u32 ncsi_calculate_checksum(unsigned char *data, int len)
 {
 	u32 checksum = 0;
@@ -213,12 +215,17 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
 {
 	struct ncsi_cmd_oem_pkt *cmd;
 	unsigned int len;
+	int payload;
+	/* NC-SI spec DSP_0222_1.2.0, section 8.2.2.2
+	 * requires payload to be padded with 0 to
+	 * 32-bit boundary before the checksum field.
+	 * Ensure the padding bytes are accounted for in
+	 * skb allocation
+	 */
 
+	payload = ALIGN(nca->payload, 4);
 	len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
-	if (nca->payload < 26)
-		len += 26;
-	else
-		len += nca->payload;
+	len += max(payload, padding_bytes);
 
 	cmd = skb_put_zero(skb, len);
 	memcpy(&cmd->mfr_id, nca->data, nca->payload);
@@ -272,6 +279,7 @@ 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 +289,14 @@ 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 following payload is
+	 * aligned to 32-bit boundary.
 	 * 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)
-		len += 26;
-	else
-		len += nca->payload;
+	payload = ALIGN(nca->payload, 4);
+	len += max(payload, padding_bytes);
 
 	/* Allocate skb */
 	skb = alloc_skb(len, GFP_ATOMIC);
-- 
2.17.1

[PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[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.

Fixes: fb4ee67529ff ("net/ncsi: Add NCSI OEM command support")
Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
Acked-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>

---
  v7:
   - Updated padding_bytes as const static int variable

  v6:
   - Updated type of padding_bytes variable
   - Updated type of payload
   - Seperated variable declarations and code

  v5:
   - Added Fixes tag
   - Added const variable for padding_bytes

  v4:
   - Used existing macro for max function

  v3:
   - Added Macro for MAX
   - Fixed the missed semicolon

  v2:
   - Added NC-SI spec version and section
   - Removed blank line
   - corrected spellings

  v1:
   - Initial draft

---
---
 net/ncsi/ncsi-cmd.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
index ba9ae482141b..9a6f10f4833e 100644
--- a/net/ncsi/ncsi-cmd.c
+++ b/net/ncsi/ncsi-cmd.c
@@ -18,6 +18,8 @@
 #include "internal.h"
 #include "ncsi-pkt.h"
 
+const static int padding_bytes = 26;
+
 u32 ncsi_calculate_checksum(unsigned char *data, int len)
 {
 	u32 checksum = 0;
@@ -213,12 +215,17 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
 {
 	struct ncsi_cmd_oem_pkt *cmd;
 	unsigned int len;
+	int payload;
+	/* NC-SI spec DSP_0222_1.2.0, section 8.2.2.2
+	 * requires payload to be padded with 0 to
+	 * 32-bit boundary before the checksum field.
+	 * Ensure the padding bytes are accounted for in
+	 * skb allocation
+	 */
 
+	payload = ALIGN(nca->payload, 4);
 	len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
-	if (nca->payload < 26)
-		len += 26;
-	else
-		len += nca->payload;
+	len += max(payload, padding_bytes);
 
 	cmd = skb_put_zero(skb, len);
 	memcpy(&cmd->mfr_id, nca->data, nca->payload);
@@ -272,6 +279,7 @@ 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 +289,14 @@ 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 following payload is
+	 * aligned to 32-bit boundary.
 	 * 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)
-		len += 26;
-	else
-		len += nca->payload;
+	payload = ALIGN(nca->payload, 4);
+	len += max(payload, padding_bytes);
 
 	/* Allocate skb */
 	skb = alloc_skb(len, GFP_ATOMIC);
-- 
2.17.1

Re: [PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[Eric Dumazet]

On 11/18/21 8:03 AM, Kumar Thangavel wrote:
> 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.
> 

Patch title should start with a prefix, identifying which layer/driver is
involved.

Probably in this case

net/ncsi: Add payload to be 32-bit aligned to fix dropped packets

> Fixes: fb4ee67529ff ("net/ncsi: Add NCSI OEM command support")
> Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
> Acked-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
> Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
> 
> ---
>   v7:
>    - Updated padding_bytes as const static int variable
> 
>   v6:
>    - Updated type of padding_bytes variable
>    - Updated type of payload
>    - Seperated variable declarations and code
> 
>   v5:
>    - Added Fixes tag
>    - Added const variable for padding_bytes
> 
>   v4:
>    - Used existing macro for max function
> 
>   v3:
>    - Added Macro for MAX
>    - Fixed the missed semicolon
> 
>   v2:
>    - Added NC-SI spec version and section
>    - Removed blank line
>    - corrected spellings
> 
>   v1:
>    - Initial draft
> 
> ---
> ---
>  net/ncsi/ncsi-cmd.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
> index ba9ae482141b..9a6f10f4833e 100644
> --- a/net/ncsi/ncsi-cmd.c
> +++ b/net/ncsi/ncsi-cmd.c
> @@ -18,6 +18,8 @@
>  #include "internal.h"
>  #include "ncsi-pkt.h"
>  
> +const static int padding_bytes = 26;

It would be nice to have some kind of reference, to explain
what is this magic value.

Moving the comment [1] here might make sense.


> +
>  u32 ncsi_calculate_checksum(unsigned char *data, int len)
>  {
>  	u32 checksum = 0;
> @@ -213,12 +215,17 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
>  {
>  	struct ncsi_cmd_oem_pkt *cmd;
>  	unsigned int len;
> +	int payload;

[1] This comment could be moved before @padding_bytes

> +	/* NC-SI spec DSP_0222_1.2.0, section 8.2.2.2
> +	 * requires payload to be padded with 0 to
> +	 * 32-bit boundary before the checksum field.
> +	 * Ensure the padding bytes are accounted for in
> +	 * skb allocation
> +	 */
>  
> +	payload = ALIGN(nca->payload, 4);
>  	len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> -	if (nca->payload < 26)
> -		len += 26;
> -	else
> -		len += nca->payload;
> +	len += max(payload, padding_bytes);
>  
>  	cmd = skb_put_zero(skb, len);
>  	memcpy(&cmd->mfr_id, nca->data, nca->payload);
> @@ -272,6 +279,7 @@ 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 +289,14 @@ 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 following payload is
> +	 * aligned to 32-bit boundary.
>  	 * 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)
> -		len += 26;
> -	else
> -		len += nca->payload;
> +	payload = ALIGN(nca->payload, 4);
> +	len += max(payload, padding_bytes);
>  
>  	/* Allocate skb */
>  	skb = alloc_skb(len, GFP_ATOMIC);
> 

Re: [PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 1902 bytes --]

Hi Kumar,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.16-rc1 next-20211118]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Kumar-Thangavel/Add-payload-to-be-32-bit-aligned-to-fix-dropped-packets/20211119-000541
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 42eb8fdac2fc5d62392dcfcf0253753e821a97b0
config: m68k-randconfig-r005-20211118 (attached as .config)
compiler: m68k-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/f4e0a51f25ba398ad7f2e3efa5076b2e0ad24e3b
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Kumar-Thangavel/Add-payload-to-be-32-bit-aligned-to-fix-dropped-packets/20211119-000541
        git checkout f4e0a51f25ba398ad7f2e3efa5076b2e0ad24e3b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=m68k 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/ncsi/ncsi-cmd.c:21:1: warning: 'static' is not at beginning of declaration [-Wold-style-declaration]
      21 | const static int padding_bytes = 26;
         | ^~~~~


vim +/static +21 net/ncsi/ncsi-cmd.c

    20	
  > 21	const static int padding_bytes = 26;
    22	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 28516 bytes --]

Re: [PATCH v7] Add payload to be 32-bit aligned to fix dropped packets

[Jakub Kicinski]

On Thu, 18 Nov 2021 21:33:02 +0530 Kumar Thangavel wrote:
> +const static int padding_bytes = 26;

/net/ncsi/ncsi-cmd.c:21:1: warning: ‘static’ is not at beginning of declaration [-Wold-style-declaration]
   21 | const static int padding_bytes = 26;
      | ^~~~~