On Tue, Apr 04, 2017 at 10:47:27AM -0700, Thomas Garnier wrote:
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 43512d4d7df2..6d598e7051c3 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -744,6 +744,10 @@ ENDPROC(cpu_switch_to)
> ret_fast_syscall:
> disable_irq // disable interrupts
> str x0, [sp, #S_X0] // returned x0
> + ldr x2, [tsk, #TSK_TI_ADDR_LIMIT] // check addr limit change
> + mov x1, #TASK_SIZE_64
> + cmp x2, x1
> + b.ne addr_limit_fail
KERNEL_DS is set to the maximum address (-1UL), so it would be easier to
check against this here and avoid a "mov". Even simpler if you'd check
against bit 63 of the address for KERNEL_DS:
ldr x1, [tsk, TSK_TI_ADDR_LIMIT] // check addr limit change
tbnz x1, #63, addr_limit_fail // KERNEL_DS is -1UL
> ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing
> and x2, x1, #_TIF_SYSCALL_WORK
> cbnz x2, ret_fast_syscall_trace
> @@ -771,6 +775,11 @@ work_pending:
> */
> ret_to_user:
> disable_irq // disable interrupts
> + ldr x2, [tsk, #TSK_TI_ADDR_LIMIT] // check addr limit change
> + mov x1, #TASK_SIZE_64
> + cmp x2, x1
> + b.ne addr_limit_fail
Same here.
> +
> ldr x1, [tsk, #TSK_TI_FLAGS]
> and x2, x1, #_TIF_WORK_MASK
> cbnz x2, work_pending
> @@ -779,6 +788,12 @@ finish_ret_to_user:
> kernel_exit 0
> ENDPROC(ret_to_user)
>
> +addr_limit_fail:
> + stp x0, lr, [sp,#-16]!
> + bl asm_verify_pre_usermode_state
> + ldp x0, lr, [sp],#16
> + ret lr
Where is this supposed to return? What is the value of lr when branching
to addr_limit_fail?
--
Catalin
