Hi, On Wed, Sep 21, 2016 at 10:28:48AM -0700, Laura Abbott wrote: > virt_addr_valid is supposed to return true if and only if virt_to_page > returns a valid page structure. The current macro does math on whatever > address is given and passes that to pfn_valid to verify. vmalloc and > module addresses can happen to generate a pfn that 'happens' to be > valid. Fix this by only performing the pfn_valid check on addresses that > have the potential to be valid. > > Signed-off-by: Laura Abbott <[email protected]> > --- > This caused a bug at least twice in hardened usercopy so it is an > actual problem.
Are there other potentially-broken users of virt_addr_valid? It's not clear to me what some drivers are doing with this, and therefore whether we need to cc stable. > A further TODO is full DEBUG_VIRTUAL support to > catch these types of mistakes. > --- > arch/arm64/include/asm/memory.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index 31b7322..f741e19 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -214,7 +214,7 @@ static inline void *phys_to_virt(phys_addr_t x) > > #ifndef CONFIG_SPARSEMEM_VMEMMAP > #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) > -#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) > +#define virt_addr_valid(kaddr) (((u64)kaddr) >= PAGE_OFFSET && > pfn_valid(__pa(kaddr) >> PAGE_SHIFT)) > #else > #define __virt_to_pgoff(kaddr) (((u64)(kaddr) & ~PAGE_OFFSET) / > PAGE_SIZE * sizeof(struct page)) > #define __page_to_voff(kaddr) (((u64)(page) & ~VMEMMAP_START) * > PAGE_SIZE / sizeof(struct page)) > @@ -222,8 +222,8 @@ static inline void *phys_to_virt(phys_addr_t x) > #define page_to_virt(page) ((void *)((__page_to_voff(page)) | PAGE_OFFSET)) > #define virt_to_page(vaddr) ((struct page *)((__virt_to_pgoff(vaddr)) | > VMEMMAP_START)) > > -#define virt_addr_valid(kaddr) pfn_valid((((u64)(kaddr) & > ~PAGE_OFFSET) \ > - + PHYS_OFFSET) >> PAGE_SHIFT) > +#define virt_addr_valid(kaddr) (((u64)kaddr) >= PAGE_OFFSET && > pfn_valid((((u64)(kaddr) & ~PAGE_OFFSET) \ > + + PHYS_OFFSET) >> PAGE_SHIFT)) > #endif > #endif Given the common sub-expression, perhaps it would be better to leave these as-is, but prefix them with '_', and after the #endif, have something like: #define _virt_addr_is_linear(kaddr) (((u64)(kaddr)) >= PAGE_OFFSET) #define virt_addr_valid(kaddr) (_virt_addr_is_linear(kaddr) && _virt_addr_valid(kaddr)) Otherwise, modulo the parenthesis issue you mentioned, this looks logically correct to me. Thanks, Mark.
