path: root/drivers/char/agp/generic.c
diff options
authorVasiliy Kulikov <segoon@openwall.com>2011-04-14 20:55:19 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-05-02 09:19:47 -0700
commit767a7e6906bd2b31c14bd57df8834da0cc81606e (patch)
tree49b395ee1d9dba80717e2f5cbb93b70c57663244 /drivers/char/agp/generic.c
parent0b7c6323a28f3fde67a26bc6b2a889d3f23b12c3 (diff)
agp: fix OOM and buffer overflow
commit b522f02184b413955f3bc952e3776ce41edc6355 upstream. 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 <segoon@openwall.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/char/agp/generic.c')
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 745e7baff3c..b072648dc3f 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) {