[PATCH v5 2/2] KEYS: asymmetric: Copy sig and digest in public_key_verify_signature()

[Eric Biggers]

On Fri, Jun 02, 2023 at 11:17:04AM +0200, Roberto Sassu wrote:
> On Thu, 2023-06-01 at 17:00 -0400, Stefan Berger wrote:
> > 
> > On 12/27/22 09:27, Roberto Sassu wrote:
> > > From: Roberto Sassu <roberto.sassu at huawei.com>
> > > 
> > > Commit ac4e97abce9b8 ("scatterlist: sg_set_buf() argument must be in linear
> > > mapping") checks that both the signature and the digest reside in the
> > > linear mapping area.
> > > 
> > > However, more recently commit ba14a194a434c ("fork: Add generic vmalloced
> > > stack support") made it possible to move the stack in the vmalloc area,
> > > which is not contiguous, and thus not suitable for sg_set_buf() which needs
> > > adjacent pages.
> > > 
> > > Always make a copy of the signature and digest in the same buffer used to
> > > store the key and its parameters, and pass them to sg_init_one(). Prefer it
> > > to conditionally doing the copy if necessary, to keep the code simple. The
> > > buffer allocated with kmalloc() is in the linear mapping area.
> > > 
> > > Cc: stable at vger.kernel.org # 4.9.x
> > > Fixes: ba14a194a434 ("fork: Add generic vmalloced stack support")
> > > Link: https://lore.kernel.org/linux-integrity/Y4pIpxbjBdajymBJ@sol.localdomain/
> > > Suggested-by: Eric Biggers <ebiggers at kernel.org>
> > > Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
> > > Reviewed-by: Eric Biggers <ebiggers at google.com>
> > 
> > I just ran into an issue with OpenBMC on ARM where EVM ECDSA signature verification failed due to invalid hashes being passed to the ECDSA signature verification algorithm. This patch here resolved the issue.
> > 
> > Tested-by: Stefan Berger <stefanb at linux.ibm.com>
> 
> Thanks, Stefan.
> 
> I did multiple attempts to have the patch included, but I didn't have
> any luck with the maintainers (David, Jarkko).
> 
> It would be awesome if any maintainer picks it.
> 
> Thanks!
> 

As the maintainers are ignoring this patch, you could try the "maintainers of
last resort" (Andrew Morton or Linus Torvalds).

- Eric