Re: [PATCH] misc: fastrpc: fix improper packet size calculation

From: Srinivas Kandagatla
Date: Mon Sep 20 2021 - 08:21:50 EST


Thanks Jeya for the fix,

On 20/09/2021 09:15, Jeya R wrote:
The buffer list is sorted and this is not being
considered while calculating packet size. This
would lead to improper copy length calculation
for non-dmaheap buffers which would eventually
cause sending improper buffers to DSP.

we need below fixes tag:

Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method")

Signed-off-by: Jeya R <jeyr@xxxxxxxxxxxxxx>
---
drivers/misc/fastrpc.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index beda610..a7e550f 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -719,16 +719,21 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
static u64 fastrpc_get_payload_size(struct fastrpc_invoke_ctx *ctx, int metalen)
{
u64 size = 0;
- int i;
+ int oix = 0;
Unnecessary initialization here.


size = ALIGN(metalen, FASTRPC_ALIGN);
- for (i = 0; i < ctx->nscalars; i++) {
+ for (oix = 0; oix < ctx->nbufs; oix++) {
+ int i = ctx->olaps[oix].raix;
+

[--
+ if (ctx->args[i].length == 0)
+ continue;
+
--]
This additional check will not really have any effect on size calculations, as (ctx->olaps[oix].mend - ctx->olaps[oix].mstart) would result in zero.
Any reason why this check was added?

--srini


if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1) {
- if (ctx->olaps[i].offset == 0)
+ if (ctx->olaps[oix].offset == 0)
size = ALIGN(size, FASTRPC_ALIGN);
- size += (ctx->olaps[i].mend - ctx->olaps[i].mstart);
+ size += (ctx->olaps[oix].mend - ctx->olaps[oix].mstart);
}
}