Messages in this thread | | | From | Jann Horn <> | Date | Mon, 9 Jul 2018 14:22:14 +0200 | Subject | Re: [PATCH v2] IB/mlx5: fix uaccess beyond "count" in debugfs read/write handlers |
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On Sun, Jul 8, 2018 at 8:56 AM Leon Romanovsky <leon@kernel.org> wrote: > > On Fri, Jul 06, 2018 at 10:48:03PM +0200, Jann Horn wrote: > > In general, accessing userspace memory beyond the length of the supplied > > buffer in VFS read/write handlers can lead to both kernel memory corruption > > (via kernel_read()/kernel_write(), which can e.g. be triggered via > > sys_splice()) and privilege escalation inside userspace. > > > > In this case, the affected files are in debugfs (and should therefore only > > be accessible to root), and the read handlers check that *pos is zero > > (meaning that at least sys_splice() can't trigger kernel memory > > corruption). Because of the root requirement, this is not a security fix, > > but rather a cleanup. > > > > For the read handlers, fix it by using simple_read_from_buffer() instead of > > custom logic. Add min() calls to the write handlers. > > > > changed in v2: > > - also fix write handlers > > No changelog in commit messages, please
I will try to do that better in the future. I never noticed that changelogs go below the three dashes...
> > Fixes: 4a2da0b8c078 ("IB/mlx5: Add debug control parameters for congestion control") > > Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters") > > Signed-off-by: Jann Horn <jannh@google.com> > > --- > > drivers/infiniband/hw/mlx5/cong.c | 9 +-------- > > drivers/infiniband/hw/mlx5/mr.c | 32 ++++++++----------------------- > > 2 files changed, 9 insertions(+), 32 deletions(-) > > > > Thanks, > Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
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