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: stable@vger.kernel.org Reported-by: Sathvika Vasireddy sathvika@linux.ibm.com Signed-off-by: Andrew Donnellan ajd@linux.ibm.com

Similar to what is done for ibm,configure-connector with idx_buf2 and a NULL address.

Reviewed-by: Tyrel Datwyler tyreld@linux.ibm.com

---

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;
  

  }