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SubjectRe: [PATCH] mptsas: fix undefined behaviour of a shift of an int by more than 31 places
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On Wed, 2019-05-08 at 14:07 +0100, Colin Ian King wrote:
> On 05/05/2019 04:34, James Bottomley wrote:
> > On Sat, 2019-05-04 at 17:40 +0100, Colin King wrote:
> > > From: Colin Ian King <colin.king@canonical.com>
> > >
> > > Currently the shift of int value 1 by more than 31 places can
> > > result in undefined behaviour. Fix this by making the 1 a ULL
> > > value before the shift operation.
> >
> > Fusion SAS is pretty ancient. I thought the largest one ever
> > produced had four phys, so how did you produce the overflow?
>
> This was an issue found by static analysis with Coverity; so I guess
> won't happen in the wild, in which case the patch could be ignored.

The point I was more making is that if we thought this could ever
happen in practice, we'd need more error handling than simply this:
we'd be setting the phy_bitmap to zero which would be every bit as bad
as some random illegal value.

James

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