ipmi: Fix kernel panic at ipmi_ssif_thread()

msg_written_handler() may set ssif_info->multi_data to NULL
when using ipmitool to write fru.

Before setting ssif_info->multi_data to NULL, add new local
pointer "data_to_send" and store correct i2c data pointer to
it to fix NULL pointer kernel panic and incorrect ssif_info->multi_pos.

Signed-off-by: Joeseph Chang <joechang@codeaurora.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: stable@vger.kernel.org # 3.19-

diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
index cca6e5bc1cea3c01831b66223f09b22fe7cf4c74..51ba67de862eb05afd9f3118e959f3e6042bf749 100644 (file)
--- a/drivers/char/ipmi/ipmi_ssif.c
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -891,6 +891,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result,
                 * for details on the intricacies of this.
                 */
                int left;
+               unsigned char *data_to_send;
 
                ssif_inc_stat(ssif_info, sent_messages_parts);
 
@@ -899,6 +900,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result,
                        left = 32;
                /* Length byte. */
                ssif_info->multi_data[ssif_info->multi_pos] = left;
+               data_to_send = ssif_info->multi_data + ssif_info->multi_pos;
                ssif_info->multi_pos += left;
                if (left < 32)
                        /*
@@ -912,7 +914,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result,
                rv = ssif_i2c_send(ssif_info, msg_written_handler,
                                  I2C_SMBUS_WRITE,
                                  SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
-                                 ssif_info->multi_data + ssif_info->multi_pos,
+                                 data_to_send,
                                  I2C_SMBUS_BLOCK_DATA);
                if (rv < 0) {
                        /* request failed, just return the error. */