From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> 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@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Reported-by: Jann Horn <jannh@xxxxxxxxxx> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> [will: fixed typo in comment] Signed-off-by: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -49,7 +49,15 @@ * 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) ? \
