Re: [PATCH] crypto: mpi: add NULL checks to mpi_normalize().

From: Herbert Xu
Date: Fri Aug 02 2024 - 08:47:22 EST


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?

Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt