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commit 7ee23491b39259ae83899dd93b2a29ef0f22f0a7 upstream. 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@linaro.org Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>