misc: fastrpc: fix possible map leak in fastrpc_put_args

copy_to_user() failure would cause an early return without cleaning up
the fdlist, which has been updated by the DSP. This could lead to map
leak. Fix this by redirecting to a cleanup path on failure, ensuring
that all mapped buffers are properly released before returning.

Fixes: c68cfb7 ("misc: fastrpc: Add support for context Invoke method")
Cc: stable@kernel.org
Co-developed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Ling Xu <quic_lxu5@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://lore.kernel.org/r/20250912131236.303102-4-srini@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: quic-lxu5

drivers/misc/fastrpc.c

@@ -1085,6 +1085,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 	struct fastrpc_phy_page *pages;
 	u64 *fdlist;
 	int i, inbufs, outbufs, handles;
+	int ret = 0;
 
 	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
 	outbufs = REMOTE_SCALARS_OUTBUFS(ctx->sc);
@@ -1100,14 +1101,17 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 			u64 len = rpra[i].buf.len;
 
 			if (!kernel) {
-				if (copy_to_user((void __user *)dst, src, len))
-					return -EFAULT;
+				if (copy_to_user((void __user *)dst, src, len)) {
+					ret = -EFAULT;
+					goto cleanup_fdlist;
+				}
 			} else {
 				memcpy(dst, src, len);
 			}
 		}
 	}
 
+cleanup_fdlist:
 	/* Clean up fdlist which is updated by DSP */
 	for (i = 0; i < FASTRPC_MAX_FDLIST; i++) {
 		if (!fdlist[i])
@@ -1116,7 +1120,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 			fastrpc_map_put(mmap);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,