On 6/14/22 06:49, Andrew Donnellan wrote:
> Add a special case to block_rtas_call() to allow the ibm,platform-dump RTAS
> call through the RTAS filter if the buffer address is 0.
>
> According to PAPR, ibm,platform-dump is called with a null buffer address
> to notify the platform firmware that processing of a particular dump is
> finished.
>
> Without this, on a pseries machine with CONFIG_PPC_RTAS_FILTER enabled, an
> application such as rtas_errd that is attempting to retrieve a dump will
> encounter an error at the end of the retrieval process.
>
> Fixes: bd59380c5ba4 ("powerpc/rtas: Restrict RTAS requests from userspace")
> Cc: sta...@vger.kernel.org
> Reported-by: Sathvika Vasireddy
> Signed-off-by: Andrew Donnellan
Similar to what is done for ibm,configure-connector with idx_buf2 and a NULL
address.
Reviewed-by: Tyrel Datwyler
> ---
> arch/powerpc/kernel/rtas.c | 11 ++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index a6fce3106e02..693133972294 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -1071,7 +1071,7 @@ static struct rtas_filter rtas_filters[]
> __ro_after_init = {
> { "get-time-of-day", -1, -1, -1, -1, -1 },
> { "ibm,get-vpd", -1, 0, -1, 1, 2 },
> { "ibm,lpar-perftools", -1, 2, 3, -1, -1 },
> - { "ibm,platform-dump", -1, 4, 5, -1, -1 },
> + { "ibm,platform-dump", -1, 4, 5, -1, -1 }, /* Special
> cased */
> { "ibm,read-slot-reset-state", -1, -1, -1, -1, -1 },
> { "ibm,scan-log-dump", -1, 0, 1, -1, -1 },
> { "ibm,set-dynamic-indicator", -1, 2, -1, -1, -1 },
> @@ -1120,6 +1120,15 @@ static bool block_rtas_call(int token, int nargs,
> size = 1;
>
> end = base + size - 1;
> +
> + /*
> + * Special case for ibm,platform-dump - NULL buffer
> + * address is used to indicate end of dump processing
> + */
> + if (!strcmp(f->name, "ibm,platform-dump") &&
> + base == 0)
> + return false;
> +
> if (!in_rmo_buf(base, end))
> goto err;
> }
