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mm/usercopy: Check kmap addresses properly

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If you are copying to an address in the kmap region, you may not copy
across a page boundary, no matter what the size of the underlying
allocation.  You can't kmap() a slab page because slab pages always
come from low memory.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220110231530.665970-2-willy@infradead.org
This commit is contained in:
Matthew Wilcox (Oracle) 2022-01-10 23:15:27 +00:00 • committed by Kees Cook
parent a19944809f
commit 4e140f59d2
3 changed files with 21 additions and 6 deletions
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10
include/linux/highmem-internal.h
View file

@ -149,6 +149,11 @@ static inline void totalhigh_pages_add(long count)
atomic_long_add(count, &_totalhigh_pages);
}
static inline bool is_kmap_addr(const void *x)
{
unsigned long addr = (unsigned long)x;
return addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP);
}
#else /* CONFIG_HIGHMEM */
static inline struct page *kmap_to_page(void *addr)
@ -234,6 +239,11 @@ static inline void __kunmap_atomic(void *addr)
static inline unsigned int nr_free_highpages(void) { return 0; }
static inline unsigned long totalhigh_pages(void) { return 0UL; }
static inline bool is_kmap_addr(const void *x)
{
return false;
}
#endif /* CONFIG_HIGHMEM */
/*