misc: fastrpc: Fix copy buffer page size

For non-registered buffer, fastrpc driver copies the buffer and
pass it to the remote subsystem. There is a problem with current
implementation of page size calculation which is not considering
the offset in the calculation. This might lead to passing of
improper and out-of-bounds page size which could result in
memory issue. Calculate page start and page end using the offset
adjusted address instead of absolute address.

Fixes: 02b45b47fbe8 ("misc: fastrpc: fix remote page size calculation")
Cc: 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/20250110134239.123603-4-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 56dc3b3a89400688f0d87a4e770d284c289a048e..7b7a22c91fe44d9348238cbde16b102eca5bf8f5 100644 (file)
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1019,8 +1019,8 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
                                        (pkt_size - rlen);
                        pages[i].addr = pages[i].addr & PAGE_MASK;
 
-                       pg_start = (args & PAGE_MASK) >> PAGE_SHIFT;
-                       pg_end = ((args + len - 1) & PAGE_MASK) >> PAGE_SHIFT;
+                       pg_start = (rpra[i].buf.pv & PAGE_MASK) >> PAGE_SHIFT;
+                       pg_end = ((rpra[i].buf.pv + len - 1) & PAGE_MASK) >> PAGE_SHIFT;
                        pages[i].size = (pg_end - pg_start + 1) * PAGE_SIZE;
                        args = args + mlen;
                        rlen -= mlen;