Messages in this thread | | | Subject | Re: [PATCH] security: keys: Use kvfree_sensitive in a few places | From | James Bottomley <> | Date | Fri, 11 Sep 2020 08:04:24 -0700 |
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On Fri, 2020-09-11 at 12:44 +0100, Alex Dewar wrote: > In big_key.c, there are a few places where memzero_explicit + kvfree > is used. It is better to use kvfree_sensitive instead, which is more > readable and also prevents the compiler from eliding the call to > memzero_explicit. Fix this.
That last bit is untrue: the compiler can't elide memzero_explicit ... that's why it has the explicit suffix.
The original problem was a lot of people do memset(.., 0, ..); kfree() which the compiler can elide if it understands the memory is going out of scope. Or the even more problematic memset(..., 0, ...) on a stack variable before it goes out of scope.
We can argue about readability but there's no secret leak here.
James
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