module: Correctly truncate sysfs sections output

The only-root-readable /sys/module/$module/sections/$section files
did not truncate their output to the available buffer size. While most
paths into the kernfs read handlers end up using PAGE_SIZE buffers,
it's possible to get there through other paths (e.g. splice, sendfile).
Actually limit the output to the "count" passed into the read function,
and report it back correctly. *sigh*

Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/20200805002015.GE23458@shao2-debian
Fixes: ed66f991bb19 ("module: Refactor section attr into bin attribute")
Cc: [email protected]
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Jessica Yu <[email protected]>
Signed-off-by: Kees Cook <[email protected]>

0 files changed, 0 insertions, 0 deletions