Messages in this thread | | | Date | Thu, 2 Oct 2014 16:23:13 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH 21/24] ARM64:ILP32: Use a seperate syscall table as a few syscalls need to be using the compat syscalls |
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On Wed, Sep 03, 2014 at 10:19:15PM +0100, Andrew Pinski wrote: > +/* > + * sigaltstack needs some special handling as the > + * padding for stack_t might not be non-zero. > + */ > +long ilp32_sys_sigaltstack(const stack_t __user *uss_ptr, > + stack_t __user *uoss_ptr) > +{ > + stack_t uss, uoss; > + int ret; > + mm_segment_t seg; > + > + if (uss_ptr) { > + if (!access_ok(VERIFY_READ, uss_ptr, sizeof(*uss_ptr))) > + return -EFAULT; > + if (__get_user(uss.ss_sp, &uss_ptr->ss_sp) | > + __get_user(uss.ss_flags, &uss_ptr->ss_flags) | > + __get_user(uss.ss_size, &uss_ptr->ss_size)) > + return -EFAULT; > + /* Zero extend the sp address and the size. */ > + uss.ss_sp = (void *)(uintptr_t)(unsigned int)(uintptr_t)uss.ss_sp;
Do you need the first (uintptr_t) cast here?
> + uss.ss_size = (size_t)(unsigned int)uss.ss_size; > + } > + seg = get_fs(); > + set_fs(KERNEL_DS); > + /* > + * Note we need to use uoss as we have changed the segment to the > + * kernel one so passing an user one around is wrong. > + */
I wonder whether it would be safe to just zero the top 32 bits of ss_sp on the user stack directly. Would we ever expect this to be read-only?
> + ret = sys_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL), > + (stack_t __force __user *) &uoss);
Nitpick: there shouldn't be any space after the type cast.
-- Catalin
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