On Sat, Oct 24, 2026 at 07:48:46PM -0700, Dmitry Torokhov wrote:
> Pass the receive buffer capacity to i2c_smbus_read_block_data() in
> ipmi_ssif_thread() via the i2c_size field, and update ssif_i2c_send()
> callers to pass the receive buffer size.
> 
> Update read_response(), do_cmd(), and test_multipart_messages() to
> accept the response buffer length, clamping the transfer size to
> I2C_SMBUS_BLOCK_MAX when reading from the device.

This is in my for-next tree.  It passes all tests.

The reuse of the "size" parameter to ssif_i2c_send() is ok.  That's not
really what it was originally meant for, it was the transaction type,
but it wasn't used, so all is good.

-corey

> 
> Signed-off-by: Dmitry Torokhov <[email protected]>
> ---
>  drivers/char/ipmi/ipmi_ssif.c | 39 +++++++++++++++++++++------------------
>  1 file changed, 21 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 2361103c5edc..9c0aebec2946 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -503,7 +503,7 @@ static int ipmi_ssif_thread(void *data)
>               } else {
>                       result = i2c_smbus_read_block_data(
>                               ssif_info->client, ssif_info->i2c_command,
> -                             ssif_info->i2c_data);
> +                             ssif_info->i2c_size, ssif_info->i2c_data);
>                       if (result < 0)
>                               ssif_info->done_handler(ssif_info, result,
>                                                       NULL, 0);
> @@ -541,7 +541,7 @@ static void start_get(struct ssif_info *ssif_info)
>  
>       ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
>                 SSIF_IPMI_RESPONSE,
> -               ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
> +               ssif_info->recv, sizeof(ssif_info->recv));
>  }
>  
>  static void start_resend(struct ssif_info *ssif_info);
> @@ -669,7 +669,7 @@ static void msg_done_handler(struct ssif_info *ssif_info, 
> int result,
>  
>               ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
>                        SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
> -                      ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
> +                      ssif_info->recv, sizeof(ssif_info->recv));
>               return;
>       } else if (ssif_info->multi_pos) {
>               /* Middle of multi-part read.  Start the next transaction. */
> @@ -736,7 +736,7 @@ static void msg_done_handler(struct ssif_info *ssif_info, 
> int result,
>                                 I2C_SMBUS_READ,
>                                 SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
>                                 ssif_info->recv,
> -                               I2C_SMBUS_BLOCK_DATA);
> +                               sizeof(ssif_info->recv));
>                       return;
>               }
>       }
> @@ -1314,12 +1314,15 @@ static void ssif_remove(struct i2c_client *client)
>       kfree(ssif_info);
>  }
>  
> -static int read_response(struct i2c_client *client, unsigned char *resp)
> +static int read_response(struct i2c_client *client, unsigned char *resp,
> +                      size_t resp_length)
>  {
>       int ret = -ENODEV, retry_cnt = SSIF_RECV_RETRIES;
>  
>       while (retry_cnt > 0) {
>               ret = i2c_smbus_read_block_data(client, SSIF_IPMI_RESPONSE,
> +                                             min_t(size_t, resp_length,
> +                                                   I2C_SMBUS_BLOCK_MAX),
>                                               resp);
>               if (ret > 0)
>                       break;
> @@ -1333,7 +1336,7 @@ static int read_response(struct i2c_client *client, 
> unsigned char *resp)
>  }
>  
>  static int do_cmd(struct i2c_client *client, int len, unsigned char *msg,
> -               int *resp_len, unsigned char *resp)
> +               int *resp_len, unsigned char *resp, size_t resp_length)
>  {
>       int retry_cnt;
>       int ret;
> @@ -1350,14 +1353,14 @@ static int do_cmd(struct i2c_client *client, int len, 
> unsigned char *msg,
>               return -ENODEV;
>       }
>  
> -     ret = read_response(client, resp);
> +     ret = read_response(client, resp, resp_length);
>       if (ret > 0) {
>               /* Validate that the response is correct. */
>               if (ret < 3 ||
>                   (resp[0] != (msg[0] | (1 << 2))) ||
>                   (resp[1] != msg[1]))
>                       ret = -EINVAL;
> -             else if (ret > IPMI_MAX_MSG_LENGTH) {
> +             else if (ret > resp_length) {
>                       ret = -E2BIG;
>               } else {
>                       *resp_len = ret;
> @@ -1382,7 +1385,7 @@ static int ssif_detect(struct i2c_client *client, 
> struct i2c_board_info *info)
>       /* Do a Get Device ID command, since it is required. */
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_GET_DEVICE_ID_CMD;
> -     rv = do_cmd(client, 2, msg, &len, resp);
> +     rv = do_cmd(client, 2, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (rv)
>               rv = -ENODEV;
>       else {
> @@ -1523,7 +1526,7 @@ static int start_multipart_test(struct i2c_client 
> *client,
>  
>  static void test_multipart_messages(struct i2c_client *client,
>                                   struct ssif_info *ssif_info,
> -                                 unsigned char *resp)
> +                                 unsigned char *resp, size_t resp_length)
>  {
>       unsigned char msg[65];
>       int ret;
> @@ -1572,7 +1575,7 @@ static void test_multipart_messages(struct i2c_client 
> *client,
>                                        1, msg + 64);
>  
>       if (!ret)
> -             ret = read_response(client, resp);
> +             ret = read_response(client, resp, resp_length);
>  
>       if (ret > 0) {
>               /* End transactions work, we are good. */
> @@ -1590,7 +1593,7 @@ static void test_multipart_messages(struct i2c_client 
> *client,
>                                        SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
>                                        0, msg + 64);
>       if (!ret)
> -             ret = read_response(client, resp);
> +             ret = read_response(client, resp, resp_length);
>       if (ret > 0)
>               /* Zero-size end parts work, use those. */
>               return;
> @@ -1748,7 +1751,7 @@ static int ssif_probe(struct i2c_client *client)
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_GET_SYSTEM_INTERFACE_CAPABILITIES_CMD;
>       msg[2] = 0; /* SSIF */
> -     rv = do_cmd(client, 3, msg, &len, resp);
> +     rv = do_cmd(client, 3, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (!rv && (len >= 3) && (resp[2] == 0)) {
>               if (len < 7) {
>                       if (ssif_dbg_probe)
> @@ -1800,13 +1803,13 @@ static int ssif_probe(struct i2c_client *client)
>               ssif_info->supports_pec = 0;
>       }
>  
> -     test_multipart_messages(client, ssif_info, resp);
> +     test_multipart_messages(client, ssif_info, resp, IPMI_MAX_MSG_LENGTH);
>  
>       /* Make sure the NMI timeout is cleared. */
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_CLEAR_MSG_FLAGS_CMD;
>       msg[2] = WDT_PRE_TIMEOUT_INT;
> -     rv = do_cmd(client, 3, msg, &len, resp);
> +     rv = do_cmd(client, 3, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (rv || (len < 3) || (resp[2] != 0))
>               dev_warn(&ssif_info->client->dev,
>                        "Unable to clear message flags: %d %d %2.2x\n",
> @@ -1815,7 +1818,7 @@ static int ssif_probe(struct i2c_client *client)
>       /* Attempt to enable the event buffer. */
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;
> -     rv = do_cmd(client, 2, msg, &len, resp);
> +     rv = do_cmd(client, 2, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (rv || (len < 4) || (resp[2] != 0)) {
>               dev_warn(&ssif_info->client->dev,
>                        "Error getting global enables: %d %d %2.2x\n",
> @@ -1835,7 +1838,7 @@ static int ssif_probe(struct i2c_client *client)
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
>       msg[2] = ssif_info->global_enables | IPMI_BMC_EVT_MSG_BUFF;
> -     rv = do_cmd(client, 3, msg, &len, resp);
> +     rv = do_cmd(client, 3, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (rv || (len < 2)) {
>               dev_warn(&ssif_info->client->dev,
>                        "Error setting global enables: %d %d %2.2x\n",
> @@ -1857,7 +1860,7 @@ static int ssif_probe(struct i2c_client *client)
>       msg[0] = IPMI_NETFN_APP_REQUEST << 2;
>       msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
>       msg[2] = ssif_info->global_enables | IPMI_BMC_RCV_MSG_INTR;
> -     rv = do_cmd(client, 3, msg, &len, resp);
> +     rv = do_cmd(client, 3, msg, &len, resp, IPMI_MAX_MSG_LENGTH);
>       if (rv || (len < 2)) {
>               dev_warn(&ssif_info->client->dev,
>                        "Error setting global enables: %d %d %2.2x\n",
> 
> -- 
> 2.56.0.257.gf7497c7d27-goog
> 


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