23be7468e8
If a futex key happens to be located within a huge page mapped MAP_PRIVATE, get_futex_key() can go into an infinite loop waiting for a page->mapping that will never exist. See https://bugzilla.redhat.com/show_bug.cgi?id=552257 for more details about the problem. This patch makes page->mapping a poisoned value that includes PAGE_MAPPING_ANON mapped MAP_PRIVATE. This is enough for futex to continue but because of PAGE_MAPPING_ANON, the poisoned value is not dereferenced or used by futex. No other part of the VM should be dereferencing the page->mapping of a hugetlbfs page as its page cache is not on the LRU. This patch fixes the problem with the test case described in the bugzilla. [akpm@linux-foundation.org: mel cant spel] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Darren Hart <darren@dvhart.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
98 lines
2.9 KiB
C
98 lines
2.9 KiB
C
#ifndef _LINUX_POISON_H
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#define _LINUX_POISON_H
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/********** include/linux/list.h **********/
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/*
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* Architectures might want to move the poison pointer offset
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* into some well-recognized area such as 0xdead000000000000,
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* that is also not mappable by user-space exploits:
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*/
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#ifdef CONFIG_ILLEGAL_POINTER_VALUE
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# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
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#else
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# define POISON_POINTER_DELTA 0
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#endif
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/*
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* These are non-NULL pointers that will result in page faults
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA)
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#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA)
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/********** include/linux/timer.h **********/
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/*
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* Magic number "tsta" to indicate a static timer initializer
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* for the object debugging code.
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*/
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#define TIMER_ENTRY_STATIC ((void *) 0x74737461)
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/********** mm/debug-pagealloc.c **********/
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#define PAGE_POISON 0xaa
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/********** mm/slab.c **********/
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/*
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* Magic nums for obj red zoning.
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* Placed in the first word before and the first word after an obj.
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*/
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#define RED_INACTIVE 0x09F911029D74E35BULL /* when obj is inactive */
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#define RED_ACTIVE 0xD84156C5635688C0ULL /* when obj is active */
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#define SLUB_RED_INACTIVE 0xbb
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#define SLUB_RED_ACTIVE 0xcc
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/* ...and for poisoning */
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#define POISON_INUSE 0x5a /* for use-uninitialised poisoning */
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#define POISON_FREE 0x6b /* for use-after-free poisoning */
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#define POISON_END 0xa5 /* end-byte of poisoning */
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/********** mm/hugetlb.c **********/
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/*
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* Private mappings of hugetlb pages use this poisoned value for
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* page->mapping. The core VM should not be doing anything with this mapping
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* but futex requires the existence of some page->mapping value even though it
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* is unused if PAGE_MAPPING_ANON is set.
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*/
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#define HUGETLB_POISON ((void *)(0x00300300 + POISON_POINTER_DELTA + PAGE_MAPPING_ANON))
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/********** arch/$ARCH/mm/init.c **********/
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#define POISON_FREE_INITMEM 0xcc
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/********** arch/ia64/hp/common/sba_iommu.c **********/
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/*
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* arch/ia64/hp/common/sba_iommu.c uses a 16-byte poison string with a
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* value of "SBAIOMMU POISON\0" for spill-over poisoning.
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*/
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/********** fs/jbd/journal.c **********/
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#define JBD_POISON_FREE 0x5b
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#define JBD2_POISON_FREE 0x5c
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/********** drivers/base/dmapool.c **********/
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#define POOL_POISON_FREED 0xa7 /* !inuse */
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#define POOL_POISON_ALLOCATED 0xa9 /* !initted */
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/********** drivers/atm/ **********/
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#define ATM_POISON_FREE 0x12
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#define ATM_POISON 0xdeadbeef
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/********** net/ **********/
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#define NEIGHBOR_DEAD 0xdeadbeef
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#define NETFILTER_LINK_POISON 0xdead57ac
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/********** kernel/mutexes **********/
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#define MUTEX_DEBUG_INIT 0x11
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#define MUTEX_DEBUG_FREE 0x22
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/********** lib/flex_array.c **********/
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#define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */
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/********** security/ **********/
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#define KEY_DESTROY 0xbd
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/********** sound/oss/ **********/
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#define OSS_POISON_FREE 0xAB
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#endif
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