Re: [PATCH AUTOSEL 4.9 75/91] RDMA/qib: Validate ->show()/store() callbacks before calling them

[Greg Kroah-Hartman]

On Tue, Dec 10, 2019 at 05:30:19PM -0500, Sasha Levin wrote:
> From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> 
> [ Upstream commit 7ee23491b39259ae83899dd93b2a29ef0f22f0a7 ]
> 
> The permissions of the read-only or write-only sysfs files can be
> changed (as root) and the user can then try to read a write-only file or
> write to a read-only file which will lead to kernel crash here.
> 
> Protect against that by always validating the show/store callbacks.
> 
> Link: https://lore.kernel.org/r/d45cc26361a174ae12dbb86c994ef334d257924b.1573096807.git.viresh.kumar@xxxxxxxxxx
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  drivers/infiniband/hw/qib/qib_sysfs.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Good catch, I was looking for this one but somehow the stable tag got
dropped from it.

greg k-h