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SubjectRe: [PATCH] ipmi: Fix kernel panic at ipmi_ssif_thread()
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This is incorrect.  These values *must* be set before ssif_i2c_send() is 
done.
Once ssif_i2c_send() is called, msg_written_handler can be called at any
time after that, including before where you moved the new code.

If I understand this correctly, I think you need to add a variable,
maybe named "bytes_to_write" and do

bytes_to_write = ssif_info->multi_data + ssif_info->multi_pos;

before the comparison and pass bytes_to_write into
ssif_i2c_send().

Thanks,

-corey

On 03/23/2017 02:07 AM, Joeseph Chang wrote:
> From: Joeseph Chang <joechang@codeaurora.org>
>
> msg_written_handler() may set ssif_info->multi_data to NULL
> when using ipmitool to write fru.
> Change the ssif i2c send data sequence in msg_written_handler()
> to fix NULL pointer kernel panic and incorrect ssif_info->multi_pos.
>
> Signed-off-by: Joeseph Chang <joechang@codeaurora.org>
> ---
> drivers/char/ipmi/ipmi_ssif.c | 20 +++++++++++---------
> 1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index cca6e5b..39346ee 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -899,21 +899,13 @@ 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;
> - ssif_info->multi_pos += left;
> - if (left < 32)
> - /*
> - * Write is finished. Note that we must end
> - * with a write of less than 32 bytes to
> - * complete the transaction, even if it is
> - * zero bytes.
> - */
> - ssif_info->multi_data = NULL;
>
> 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,
> I2C_SMBUS_BLOCK_DATA);
> +
> if (rv < 0) {
> /* request failed, just return the error. */
> ssif_inc_stat(ssif_info, send_errors);
> @@ -922,6 +914,16 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result,
> pr_info("Error from i2c_non_blocking_op(3)\n");
> msg_done_handler(ssif_info, -EIO, NULL, 0);
> }
> +
> + ssif_info->multi_pos += left;
> + if (left < 32)
> + /*
> + * Write is finished. Note that we must end
> + * with a write of less than 32 bytes to
> + * complete the transaction, even if it is
> + * zero bytes.
> + */
> + ssif_info->multi_data = NULL;
> } else {
> /* Ready to request the result. */
> unsigned long oflags, *flags;


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