Date: Tue, 9 Apr 2013 19:15:59 +0200 From: Oliver Pinter <oliver.pntr@gmail.com> To: Vijay Singh <vijju.singh@gmail.com> Cc: hackers@freebsd.org Subject: Re: copyinstr() Message-ID: <CAPjTQNG-jVyA2K8Oo1q%2BkQZNTU1zj10VPYDXkHVysA-29Ovmfw@mail.gmail.com> In-Reply-To: <CALCNsJTtf5UCwGXb5eO8kESQG9GFqyT8%2B6BXdTjfzJ%2BjLW=_CQ@mail.gmail.com> References: <CALCNsJTtf5UCwGXb5eO8kESQG9GFqyT8%2B6BXdTjfzJ%2BjLW=_CQ@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 4/9/13, Vijay Singh <vijju.singh@gmail.com> wrote:
> Hi, I was looking for some help with copyinstr() on an amd64 platform.
>
> My from address happens to be in the kernel (stack). I am getting an
> EFAULT, and I am wondering how to fix that.
>
> Would using memory from malloc() make a difference?
The copyinstr check the address before do anything.
amd64/support.S:
/*
* copyinstr(from, to, maxlen, int *lencopied) - MP SAFE
* %rdi, %rsi, %rdx, %rcx
*
* copy a string from from to to, stop when a 0 character is reached.
* return ENAMETOOLONG if string is longer than maxlen, and
* EFAULT on protection violations. If lencopied is non-zero,
* return the actual length in *lencopied.
*/
ENTRY(copyinstr)
movq %rdx,%r8 /* %r8 = maxlen */
movq %rcx,%r9 /* %r9 = *len */
xchgq %rdi,%rsi /* %rdi = from, %rsi = to */
movq PCPU(CURPCB),%rcx
movq $cpystrflt,PCB_ONFAULT(%rcx)
movq $VM_MAXUSER_ADDRESS,%rax
/* make sure 'from' is within bounds */
subq %rsi,%rax
jbe cpystrfl
[...]
cpystrflt:
movq $EFAULT,%rax
[...]
Try copyout() instead of copyinstr(), as there in amd64 are no copyoutstr().
>
> -vijay
> _______________________________________________
> freebsd-hackers@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAPjTQNG-jVyA2K8Oo1q%2BkQZNTU1zj10VPYDXkHVysA-29Ovmfw>