lkml.org 
[lkml]   [2018]   [Dec]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/2] riscv: fix syscall_{get,set}_arguments
On Thu, Dec 6, 2018 at 5:49 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Thu, Dec 6, 2018 at 7:02 AM David Abdurachmanov
> <david.abdurachmanov@gmail.com> wrote:
> >
> > Testing with libseccomp master branch revealed that testcases with
> > filters on syscall arguments were failing due to wrong values. Seccomp
> > uses syscall_get_argumentsi() to copy syscall arguments, and there is a
> > bug in pointer arithmetics in memcpy() call.
> >
> > Two alternative implementation were tested: the one in this patch and
> > another one based on while-break loop. Both delivered the same results.
> >
> > This implementation is also used in arm, arm64 and nds32 arches.
>
> Minor nit: can you make this the first patch? That way seccomp works
> correctly from the point of introduction. :)

Ok. I will do it.

david

>
> -Kees
>
> >
> > Signed-off-by: David Abdurachmanov <david.abdurachmanov@gmail.com>
> > ---
> > arch/riscv/include/asm/syscall.h | 42 ++++++++++++++++++++++++--------
> > 1 file changed, 32 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
> > index bba3da6ef157..26ceb434a433 100644
> > --- a/arch/riscv/include/asm/syscall.h
> > +++ b/arch/riscv/include/asm/syscall.h
> > @@ -70,19 +70,32 @@ static inline void syscall_set_return_value(struct task_struct *task,
> > regs->a0 = (long) error ?: val;
> > }
> >
> > +#define SYSCALL_MAX_ARGS 6
> > +
> > static inline void syscall_get_arguments(struct task_struct *task,
> > struct pt_regs *regs,
> > unsigned int i, unsigned int n,
> > unsigned long *args)
> > {
> > - BUG_ON(i + n > 6);
> > + if (n == 0)
> > + return;
> > +
> > + if (i + n > SYSCALL_MAX_ARGS) {
> > + unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
> > + unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
> > + pr_warning("%s called with max args %d, handling only %d\n",
> > + __func__, i + n, SYSCALL_MAX_ARGS);
> > + memset(args_bad, 0, n_bad * sizeof(args[0]));
> > + }
> > +
> > if (i == 0) {
> > args[0] = regs->orig_a0;
> > args++;
> > i++;
> > n--;
> > }
> > - memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
> > +
> > + memcpy(args, &regs->a0 + i, n * sizeof(args[0]));
> > }
> >
> > static inline void syscall_set_arguments(struct task_struct *task,
> > @@ -90,14 +103,23 @@ static inline void syscall_set_arguments(struct task_struct *task,
> > unsigned int i, unsigned int n,
> > const unsigned long *args)
> > {
> > - BUG_ON(i + n > 6);
> > - if (i == 0) {
> > - regs->orig_a0 = args[0];
> > - args++;
> > - i++;
> > - n--;
> > - }
> > - memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
> > + if (n == 0)
> > + return;
> > +
> > + if (i + n > SYSCALL_MAX_ARGS) {
> > + pr_warning("%s called with max args %d, handling only %d\n",
> > + __func__, i + n, SYSCALL_MAX_ARGS);
> > + n = SYSCALL_MAX_ARGS - i;
> > + }
> > +
> > + if (i == 0) {
> > + regs->orig_a0 = args[0];
> > + args++;
> > + i++;
> > + n--;
> > + }
> > +
> > + memcpy(&regs->a0 + i, args, n * sizeof(args[0]));
> > }
> >
> > static inline int syscall_get_arch(void)
> > --
> > 2.19.2
> >
>
>
> --
> Kees Cook

\
 
 \ /
  Last update: 2018-12-06 18:14    [W:0.045 / U:1.812 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site