gpu: host1x: Check reloc table before usage

The firewall assumed that the user space always delivers a relocation
table when it is accessing address registers. If userspace did not
deliver a relocation table and tried to access the address registers,
the code performed bad memory accesses.

This patch modifies the firewall to check correctly that the firewall
table is available before accessing it. In addition, check_reloc() is
converted to use boolean return value (true when the reloc is valid,
false when invalid).
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Acked-By: Terje Bergstrom <tbergstrom@nvidia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/gpu/host1x/job.c

@@ -268,15 +268,15 @@ static unsigned int do_relocs(struct host1x_job *job, struct host1x_bo *cmdbuf)
 	return 0;
 }
 
-static int check_reloc(struct host1x_reloc *reloc, struct host1x_bo *cmdbuf,
+static bool check_reloc(struct host1x_reloc *reloc, struct host1x_bo *cmdbuf,
 		       unsigned int offset)
 {
 	offset *= sizeof(u32);
 
 	if (reloc->cmdbuf != cmdbuf || reloc->cmdbuf_offset != offset)
-		return -EINVAL;
+		return false;
 
-	return 0;
+	return true;
 }
 
 struct host1x_firewall {
@@ -307,10 +307,10 @@ static int check_mask(struct host1x_firewall *fw)
 
 		if (mask & 1) {
 			if (fw->job->is_addr_reg(fw->dev, fw->class, reg)) {
-				bool bad_reloc = check_reloc(fw->reloc,
-							     fw->cmdbuf_id,
-							     fw->offset);
-				if (!fw->num_relocs || bad_reloc)
+				if (!fw->num_relocs)
+					return -EINVAL;
+				if (!check_reloc(fw->reloc, fw->cmdbuf_id,
+						 fw->offset))
 					return -EINVAL;
 				fw->reloc++;
 				fw->num_relocs--;
@@ -335,9 +335,9 @@ static int check_incr(struct host1x_firewall *fw)
 			return -EINVAL;
 
 		if (fw->job->is_addr_reg(fw->dev, fw->class, reg)) {
-			bool bad_reloc = check_reloc(fw->reloc, fw->cmdbuf_id,
-						     fw->offset);
-			if (!fw->num_relocs || bad_reloc)
+			if (!fw->num_relocs)
+				return -EINVAL;
+			if (!check_reloc(fw->reloc, fw->cmdbuf_id, fw->offset))
 				return -EINVAL;
 			fw->reloc++;
 			fw->num_relocs--;
@@ -361,9 +361,9 @@ static int check_nonincr(struct host1x_firewall *fw)
 			return -EINVAL;
 
 		if (is_addr_reg) {
-			bool bad_reloc = check_reloc(fw->reloc, fw->cmdbuf_id,
-						     fw->offset);
-			if (!fw->num_relocs || bad_reloc)
+			if (!fw->num_relocs)
+				return -EINVAL;
+			if (!check_reloc(fw->reloc, fw->cmdbuf_id, fw->offset))
 				return -EINVAL;
 			fw->reloc++;
 			fw->num_relocs--;