57 lines
2.2 KiB
Diff
57 lines
2.2 KiB
Diff
From: Vasiliy Kulikov <segoon@openwall.com>
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Date: Thu, 14 Apr 2011 16:55:19 +0000 (+0400)
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Subject: agp: fix OOM and buffer overflow
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X-Git-Tag: v2.6.39-rc5~29^2~1
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=b522f02184b413955f3bc952e3776ce41edc6355
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agp: fix OOM and buffer overflow
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page_count is copied from userspace. agp_allocate_memory() tries to
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check whether this number is too big, but doesn't take into account the
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wrap case. Also agp_create_user_memory() doesn't check whether
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alloc_size is calculated from num_agp_pages variable without overflow.
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This may lead to allocation of too small buffer with following buffer
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overflow.
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Another problem in agp code is not addressed in the patch - kernel memory
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exhaustion (AGPIOC_RESERVE and AGPIOC_ALLOCATE ioctls). It is not checked
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whether requested pid is a pid of the caller (no check in agpioc_reserve_wrap()).
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Each allocation is limited to 16KB, though, there is no per-process limit.
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This might lead to OOM situation, which is not even solved in case of the
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caller death by OOM killer - the memory is allocated for another (faked) process.
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Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
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Signed-off-by: Dave Airlie <airlied@redhat.com>
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---
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diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
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index 012cba0..850a643 100644
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--- a/drivers/char/agp/generic.c
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+++ b/drivers/char/agp/generic.c
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@@ -115,6 +115,9 @@ static struct agp_memory *agp_create_user_memory(unsigned long num_agp_pages)
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struct agp_memory *new;
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unsigned long alloc_size = num_agp_pages*sizeof(struct page *);
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+ if (INT_MAX/sizeof(struct page *) < num_agp_pages)
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+ return NULL;
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+
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new = kzalloc(sizeof(struct agp_memory), GFP_KERNEL);
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if (new == NULL)
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return NULL;
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@@ -234,11 +237,14 @@ struct agp_memory *agp_allocate_memory(struct agp_bridge_data *bridge,
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int scratch_pages;
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struct agp_memory *new;
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size_t i;
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+ int cur_memory;
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if (!bridge)
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return NULL;
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- if ((atomic_read(&bridge->current_memory_agp) + page_count) > bridge->max_memory_agp)
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+ cur_memory = atomic_read(&bridge->current_memory_agp);
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+ if ((cur_memory + page_count > bridge->max_memory_agp) ||
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+ (cur_memory + page_count < page_count))
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return NULL;
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if (type >= AGP_USER_TYPES) {
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