56 lines
2.0 KiB
Diff
56 lines
2.0 KiB
Diff
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From: Vasiliy Kulikov <segoon@openwall.com>
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Date: Thu, 14 Apr 2011 16:55:16 +0000 (+0400)
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Subject: agp: fix arbitrary kernel memory writes
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X-Git-Tag: v2.6.39-rc5~29^2
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=194b3da873fd334ef183806db751473512af29ce
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agp: fix arbitrary kernel memory writes
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pg_start is copied from userspace on AGPIOC_BIND and AGPIOC_UNBIND ioctl
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cmds of agp_ioctl() and passed to agpioc_bind_wrap(). As said in the
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comment, (pg_start + mem->page_count) may wrap in case of AGPIOC_BIND,
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and it is not checked at all in case of AGPIOC_UNBIND. As a result, user
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with sufficient privileges (usually "video" group) may generate either
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local DoS or privilege escalation.
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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 850a643..b072648 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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@@ -1095,8 +1095,8 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type)
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return -EINVAL;
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}
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- /* AK: could wrap */
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- if ((pg_start + mem->page_count) > num_entries)
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+ if (((pg_start + mem->page_count) > num_entries) ||
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+ ((pg_start + mem->page_count) < pg_start))
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return -EINVAL;
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j = pg_start;
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@@ -1130,7 +1130,7 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
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{
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size_t i;
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struct agp_bridge_data *bridge;
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- int mask_type;
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+ int mask_type, num_entries;
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bridge = mem->bridge;
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if (!bridge)
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@@ -1142,6 +1142,11 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
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if (type != mem->type)
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return -EINVAL;
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+ num_entries = agp_num_entries();
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+ if (((pg_start + mem->page_count) > num_entries) ||
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+ ((pg_start + mem->page_count) < pg_start))
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+ return -EINVAL;
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+
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mask_type = bridge->driver->agp_type_to_mask_type(bridge, type);
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if (mask_type != 0) {
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/* The generic routines know nothing of memory types */
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