From b522f02184b413955f3bc952e3776ce41edc6355 Mon Sep 17 00:00:00 2001 From: Vasiliy Kulikov Date: Thu, 14 Apr 2011 20:55:19 +0400 Subject: agp: fix OOM and buffer overflow page_count is copied from userspace. agp_allocate_memory() tries to check whether this number is too big, but doesn't take into account the wrap case. Also agp_create_user_memory() doesn't check whether alloc_size is calculated from num_agp_pages variable without overflow. This may lead to allocation of too small buffer with following buffer overflow. Another problem in agp code is not addressed in the patch - kernel memory exhaustion (AGPIOC_RESERVE and AGPIOC_ALLOCATE ioctls). It is not checked whether requested pid is a pid of the caller (no check in agpioc_reserve_wrap()). Each allocation is limited to 16KB, though, there is no per-process limit. This might lead to OOM situation, which is not even solved in case of the caller death by OOM killer - the memory is allocated for another (faked) process. Signed-off-by: Vasiliy Kulikov Signed-off-by: Dave Airlie --- drivers/char/agp/generic.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/char/agp/generic.c') diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c index 012cba0..850a643 100644 --- a/drivers/char/agp/generic.c +++ b/drivers/char/agp/generic.c @@ -115,6 +115,9 @@ static struct agp_memory *agp_create_user_memory(unsigned long num_agp_pages) struct agp_memory *new; unsigned long alloc_size = num_agp_pages*sizeof(struct page *); + if (INT_MAX/sizeof(struct page *) < num_agp_pages) + return NULL; + new = kzalloc(sizeof(struct agp_memory), GFP_KERNEL); if (new == NULL) return NULL; @@ -234,11 +237,14 @@ struct agp_memory *agp_allocate_memory(struct agp_bridge_data *bridge, int scratch_pages; struct agp_memory *new; size_t i; + int cur_memory; if (!bridge) return NULL; - if ((atomic_read(&bridge->current_memory_agp) + page_count) > bridge->max_memory_agp) + cur_memory = atomic_read(&bridge->current_memory_agp); + if ((cur_memory + page_count > bridge->max_memory_agp) || + (cur_memory + page_count < page_count)) return NULL; if (type >= AGP_USER_TYPES) { -- cgit v1.1 From 194b3da873fd334ef183806db751473512af29ce Mon Sep 17 00:00:00 2001 From: Vasiliy Kulikov Date: Thu, 14 Apr 2011 20:55:16 +0400 Subject: 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: Vasiliy Kulikov Signed-off-by: Dave Airlie --- drivers/char/agp/generic.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'drivers/char/agp/generic.c') diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c index 850a643..b072648 100644 --- a/drivers/char/agp/generic.c +++ b/drivers/char/agp/generic.c @@ -1095,8 +1095,8 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type) 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; j = pg_start; @@ -1130,7 +1130,7 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type) { size_t i; struct agp_bridge_data *bridge; - int mask_type; + int mask_type, num_entries; bridge = mem->bridge; if (!bridge) @@ -1142,6 +1142,11 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type) if (type != mem->type) 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); if (mask_type != 0) { /* The generic routines know nothing of memory types */ -- cgit v1.1