On Fri, 2024-08-02 at 20:46 +0800, Herbert Xu wrote:
> On Tue, Jul 16, 2024 at 11:28:25AM +0300, Roman Smirnov wrote:
> > If a->d is NULL, the NULL pointer will be dereferenced. It
> > is necessary to prevent this case. There is at least one call
> > stack that can lead to it:
> >
> > mpi_ec_curve_point()
> > ec_pow2()
> > ec_mulm()
> > ec_mod()
> > mpi_mod()
> > mpi_fdiv_r()
> > mpi_tdiv_r()
> > mpi_tdiv_qr()
> > mpi_resize()
> > kcalloc()
> >
> > mpi_resize can return -ENOMEM, but this case is not handled in any way.
> >
> > Next, dereferencing takes place:
> >
> > mpi_ec_curve_point()
> > mpi_cmp()
> > do_mpi_cmp()
> > mpi_normalize()
> >
> > Found by Linux Verification Center (linuxtesting.org) with Svace.
> >
> > Signed-off-by: Roman Smirnov <r.smirnov@xxxxxx>
> > ---
> > lib/crypto/mpi/mpi-bit.c | 3 +++
> > 1 file changed, 3 insertions(+)
>
> I've just posted a patch to remove mpi_ec_curve_point and mpi_tdiv_qr.
> Are there any other code paths with the same problem?
Svace found a similar case but it is no longer relevant:
NULL constant:
mpi_ec_mul_point()
ec_mulm(z3, point->z, z2, ctx)
ec_mod()
mpi_mod()
mpi_fdiv_r()
mpi_tdiv_r()
mpi_tdiv_qr()
mpi_resize()
kcalloc()
Dereference:
mpi_ec_mul_point()
ec_invm(z3, z3, ctx)
mpi_invm()
mpi_cmp_ui()
mpi_normalize()
>
> Thanks,
