Commit 194b3da8 authored by Vasiliy Kulikov's avatar Vasiliy Kulikov Committed by Dave Airlie

agp: fix arbitrary kernel memory writes

pg_start is copied from userspace on AGPIOC_BIND and AGPIOC_UNBIND ioctl
cmds of agp_ioctl() and passed to agpioc_bind_wrap().  As said in the
comment, (pg_start + mem->page_count) may wrap in case of AGPIOC_BIND,
and it is not checked at all in case of AGPIOC_UNBIND.  As a result, user
with sufficient privileges (usually "video" group) may generate either
local DoS or privilege escalation.
Signed-off-by: default avatarVasiliy Kulikov <segoon@openwall.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent b522f021
...@@ -1095,8 +1095,8 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type) ...@@ -1095,8 +1095,8 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type)
return -EINVAL; return -EINVAL;
} }
/* AK: could wrap */ if (((pg_start + mem->page_count) > num_entries) ||
if ((pg_start + mem->page_count) > num_entries) ((pg_start + mem->page_count) < pg_start))
return -EINVAL; return -EINVAL;
j = pg_start; j = pg_start;
...@@ -1130,7 +1130,7 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type) ...@@ -1130,7 +1130,7 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
{ {
size_t i; size_t i;
struct agp_bridge_data *bridge; struct agp_bridge_data *bridge;
int mask_type; int mask_type, num_entries;
bridge = mem->bridge; bridge = mem->bridge;
if (!bridge) if (!bridge)
...@@ -1142,6 +1142,11 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type) ...@@ -1142,6 +1142,11 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
if (type != mem->type) if (type != mem->type)
return -EINVAL; return -EINVAL;
num_entries = agp_num_entries();
if (((pg_start + mem->page_count) > num_entries) ||
((pg_start + mem->page_count) < pg_start))
return -EINVAL;
mask_type = bridge->driver->agp_type_to_mask_type(bridge, type); mask_type = bridge->driver->agp_type_to_mask_type(bridge, type);
if (mask_type != 0) { if (mask_type != 0) {
/* The generic routines know nothing of memory types */ /* The generic routines know nothing of memory types */
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment