On Mon, 2012-10-08 at 11:09 -0400, Dave Jones wrote:

Last month I sent in 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a to remove
a user triggerable BUG in mempolicy.

Ben Hutchings pointed out to me that my change introduced a potential leak
of stack contents to userspace, because none of the callers check the return value.

This patch adds the missing return checking, and also clears the buffer beforehand.

Reported-by: Ben Hutchings <redacted>

I was wearing my other hat at the time (ben@decadent.org.uk).

Cc: stable@kernel.org
Signed-off-by: Dave Jones <redacted>

--- 
unanswered question: why are the buffer sizes here different ? which is correct?

[...]

Further question: why even use an intermediate buffer on the stack?
Both callers want to write the result to a seq_file.  Should mpol_str()
then be replaced with a seq_mpol()?

Ben.

-- 
Ben Hutchings
Who are all these weirdos? - David Bowie, about L-Space IRC channel #afp