[PATCH v1 2/3] misc: fastrpc: Fix fastrpc_map_lookup operation

[Ekansh Gupta]

Fastrpc driver creates maps for user allocated fd buffers. Before
creating a new map, the map list is checked for any already existing
maps using map fd. Checking with just map fd is not sufficient as the
user can pass offsetted buffer with less size when the map is created
and then a larger size the next time which could result in memory
issues. Check for user passed VA and length also when looking up for
the map.

Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method")
Cc: stable <stable at kernel.org>
Signed-off-by: Ekansh Gupta <quic_ekangupt at quicinc.com>
---
 drivers/misc/fastrpc.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index bcfb8ce1a0e3..ebe828770a8d 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -362,7 +362,8 @@ static int fastrpc_map_get(struct fastrpc_map *map)
 
 
 static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd,
-			    struct fastrpc_map **ppmap, bool take_ref)
+			    u64 va, u64 len, struct fastrpc_map **ppmap,
+				bool take_ref)
 {
 	struct fastrpc_session_ctx *sess = fl->sctx;
 	struct fastrpc_map *map = NULL;
@@ -370,7 +371,8 @@ static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd,
 
 	spin_lock(&fl->lock);
 	list_for_each_entry(map, &fl->maps, node) {
-		if (map->fd != fd)
+		if (map->fd != fd || va < (u64)map->va ||
+			va + len > (u64)map->va + map->size)
 			continue;
 
 		if (take_ref) {
@@ -752,7 +754,8 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = {
 };
 
 static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
-			      u64 len, u32 attr, struct fastrpc_map **ppmap)
+				u64 va, u64 len, u32 attr,
+				struct fastrpc_map **ppmap)
 {
 	struct fastrpc_session_ctx *sess = fl->sctx;
 	struct fastrpc_map *map = NULL;
@@ -760,7 +763,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
 	struct scatterlist *sgl = NULL;
 	int err = 0, sgl_index = 0;
 
-	if (!fastrpc_map_lookup(fl, fd, ppmap, true))
+	if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, true))
 		return 0;
 
 	map = kzalloc(sizeof(*map), GFP_KERNEL);
@@ -807,7 +810,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
 		err = -EINVAL;
 		goto map_err;
 	}
-	map->va = sg_virt(map->table->sgl);
+	map->va = (void *)(uintptr_t)va;
 	map->len = len;
 
 	if (attr & FASTRPC_ATTR_SECUREMAP) {
@@ -920,7 +923,8 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx)
 			continue;
 
 		err = fastrpc_map_create(ctx->fl, ctx->args[i].fd,
-			 ctx->args[i].length, ctx->args[i].attr, &ctx->maps[i]);
+				(u64)ctx->args[i].ptr, ctx->args[i].length,
+				ctx->args[i].attr, &ctx->maps[i]);
 		if (err) {
 			dev_err(dev, "Error Creating map %d\n", err);
 			return -EINVAL;
@@ -1106,7 +1110,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 	for (i = 0; i < FASTRPC_MAX_FDLIST; i++) {
 		if (!fdlist[i])
 			break;
-		if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false))
+		if (!fastrpc_map_lookup(fl, (int)fdlist[i], 0, 0, &mmap, false))
 			fastrpc_map_put(mmap);
 	}
 
@@ -1412,7 +1416,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
 	fl->pd = USER_PD;
 
 	if (init.filelen && init.filefd) {
-		err = fastrpc_map_create(fl, init.filefd, init.filelen, 0, &map);
+		err = fastrpc_map_create(fl, init.filefd, init.file,
+				init.filelen, 0, &map);
 		if (err)
 			goto err;
 	}
@@ -2034,7 +2039,8 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
 		return -EFAULT;
 
 	/* create SMMU mapping */
-	err = fastrpc_map_create(fl, req.fd, req.length, 0, &map);
+	err = fastrpc_map_create(fl, req.fd, req.vaddrin, req.length,
+			0, &map);
 	if (err) {
 		dev_err(dev, "failed to map buffer, fd = %d\n", req.fd);
 		return err;
-- 
2.34.1