misc: fastrpc: Reset metadata buffer to avoid incorrect free

commit 1c29d80134ac116e0196c7bad58a2121381b679c upstream.

Metadata buffer is allocated during get_args for any remote call.
This buffer carries buffers, fdlists and other payload information
for the call. If the buffer is not reset, put_args might find some
garbage FDs in the fdlist which might have an existing mapping in
the list. This could result in improper freeing of FD map when DSP
might still be using the buffer. Added change to reset the metadata
buffer after allocation.

Fixes: 8f6c1d8c4f0c ("misc: fastrpc: Add fdlist implementation")
Cc: stable <stable@kernel.org>
Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20231013122007.174464-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 42c4f603ec81fdcc320c6bf4df0af1a5ac640bf0..25e5e72cc2b28239f5d3c56ca25314b92da688f5 100644 (file)
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -957,6 +957,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
        if (err)
                return err;
 
+       memset(ctx->buf->virt, 0, pkt_size);
        rpra = ctx->buf->virt;
        list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
        pages = fastrpc_phy_page_start(list, ctx->nscalars);