misc: fastrpc: Save actual DMA size in fastrpc_map structure

For user passed fd buffer, map is created using DMA calls. The
map related information is stored in fastrpc_map structure. The
actual DMA size is not stored in the structure. Store the actual
size of buffer and check it against the user passed size.

Fixes: c68cfb7 ("misc: fastrpc: Add support for context Invoke method")
Cc: stable@kernel.org
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
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@linaro.org>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://lore.kernel.org/r/20250912131236.303102-2-srini@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: quic-lxu5

drivers/misc/fastrpc.c

@@ -323,11 +323,11 @@ static void fastrpc_free_map(struct kref *ref)
 
 			perm.vmid = QCOM_SCM_VMID_HLOS;
 			perm.perm = QCOM_SCM_PERM_RWX;
-			err = qcom_scm_assign_mem(map->phys, map->size,
+			err = qcom_scm_assign_mem(map->phys, map->len,
 				&src_perms, &perm, 1);
 			if (err) {
 				dev_err(map->fl->sctx->dev, "Failed to assign memory phys 0x%llx size 0x%llx err %d\n",
-						map->phys, map->size, err);
+						map->phys, map->len, err);
 				return;
 			}
 		}
@@ -758,7 +758,8 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
 	struct fastrpc_session_ctx *sess = fl->sctx;
 	struct fastrpc_map *map = NULL;
 	struct sg_table *table;
-	int err = 0;
+	struct scatterlist *sgl = NULL;
+	int err = 0, sgl_index = 0;
 
 	if (!fastrpc_map_lookup(fl, fd, ppmap, true))
 		return 0;
@@ -798,7 +799,15 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
 		map->phys = sg_dma_address(map->table->sgl);
 		map->phys += ((u64)fl->sctx->sid << 32);
 	}
-	map->size = len;
+	for_each_sg(map->table->sgl, sgl, map->table->nents,
+		sgl_index)
+		map->size += sg_dma_len(sgl);
+	if (len > map->size) {
+		dev_dbg(sess->dev, "Bad size passed len 0x%llx map size 0x%llx\n",
+				len, map->size);
+		err = -EINVAL;
+		goto map_err;
+	}
 	map->va = sg_virt(map->table->sgl);
 	map->len = len;
 
@@ -815,10 +824,10 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
 		dst_perms[1].vmid = fl->cctx->vmperms[0].vmid;
 		dst_perms[1].perm = QCOM_SCM_PERM_RWX;
 		map->attr = attr;
-		err = qcom_scm_assign_mem(map->phys, (u64)map->size, &src_perms, dst_perms, 2);
+		err = qcom_scm_assign_mem(map->phys, (u64)map->len, &src_perms, dst_perms, 2);
 		if (err) {
 			dev_err(sess->dev, "Failed to assign memory with phys 0x%llx size 0x%llx err %d\n",
-					map->phys, map->size, err);
+					map->phys, map->len, err);
 			goto map_err;
 		}
 	}
@@ -2046,7 +2055,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
 	args[0].length = sizeof(req_msg);
 
 	pages.addr = map->phys;
-	pages.size = map->size;
+	pages.size = map->len;
 
 	args[1].ptr = (u64) (uintptr_t) &pages;
 	args[1].length = sizeof(pages);
@@ -2061,7 +2070,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
 	err = fastrpc_internal_invoke(fl, true, FASTRPC_INIT_HANDLE, sc, &args[0]);
 	if (err) {
 		dev_err(dev, "mem mmap error, fd %d, vaddr %llx, size %lld\n",
-			req.fd, req.vaddrin, map->size);
+			req.fd, req.vaddrin, map->len);
 		goto err_invoke;
 	}
 
@@ -2074,7 +2083,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
 	if (copy_to_user((void __user *)argp, &req, sizeof(req))) {
 		/* unmap the memory and release the buffer */
 		req_unmap.vaddr = (uintptr_t) rsp_msg.vaddr;
-		req_unmap.length = map->size;
+		req_unmap.length = map->len;
 		fastrpc_req_mem_unmap_impl(fl, &req_unmap);
 		return -EFAULT;
 	}