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| author | Vasiliy Kulikov <segoon@openwall.com> | 2011-04-14 18:55:19 +0200 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2011-04-21 03:51:04 +0200 |
| commit | b522f02184b413955f3bc952e3776ce41edc6355 (patch) | |
| tree | 3141d04c93d5342c06e54bbba389b646a005cb04 /drivers/char | |
| parent | drm/radeon/kms: fix IH writeback on r6xx+ on big endian machines (diff) | |
| download | linux-b522f02184b413955f3bc952e3776ce41edc6355.tar.xz linux-b522f02184b413955f3bc952e3776ce41edc6355.zip | |
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 <segoon@openwall.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/agp/generic.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c index 012cba0d6d96..850a643ad694 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) { |