From: Vincenzo Frascino vincenzo.frascino@arm.com
commit d263119387de9975d2acba1dfd3392f7c5979c18 upstream.
Currently, compat tasks running on arm64 can allocate memory up to TASK_SIZE_32 (UL(0x100000000)).
This means that mmap() allocations, if we treat them as returning an array, are not compliant with the sections 6.5.8 of the C standard (C99) which states that: "If the expression P points to an element of an array object and the expression Q points to the last element of the same array object, the pointer expression Q+1 compares greater than P".
Redefine TASK_SIZE_32 to address the issue.
Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will.deacon@arm.com Cc: Jann Horn jannh@google.com Cc: stable@vger.kernel.org Reported-by: Jann Horn jannh@google.com Signed-off-by: Vincenzo Frascino vincenzo.frascino@arm.com [will: fixed typo in comment] Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm64/include/asm/processor.h | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -53,7 +53,15 @@ * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area. */ #ifdef CONFIG_COMPAT +#ifdef CONFIG_ARM64_64K_PAGES +/* + * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied + * by the compat vectors page. + */ #define TASK_SIZE_32 UL(0x100000000) +#else +#define TASK_SIZE_32 (UL(0x100000000) - PAGE_SIZE) +#endif /* CONFIG_ARM64_64K_PAGES */ #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ TASK_SIZE_32 : TASK_SIZE_64) #define TASK_SIZE_OF(tsk) (test_tsk_thread_flag(tsk, TIF_32BIT) ? \