Re: [PATCH V3] xfsdump: prevent segfault in cb_add_inogrp

[Dave Chinner <david@fromorbit.com>]

On Wed, Aug 26, 2015 at 05:29:55PM -0500, rjohnston@sgi.com wrote:
> 
> The call to memset will segfault because the offset for the first
> parameter is done twice. We are using pointer math to do the
> calculation.
> 
> The first time is when calculating oldsize, the size of i2gseg_t
> is accounted for.
> 	oldsize = (numsegs - SEGPERHNK) * sizeof(i2gseg_t);
> Then in the call to memset, oldsize is again multiplied by the size
> of i2gmap_t.
> 	memset(inomap.i2gmap + oldsize, ...)
> 	
> i2gmap holds the used inodes in each chunk. When there are 2^31 chunk
> entries, it could describe 2^31 (1 inode/chunk)- 2^40 (64 inodes/chunk).
> 
> With 100s of millions of inodes there are enough entries to wrap the
> 32 bit variable oldsize.
> 
> Adding a bounds check (numsegs < 0) and switching to use array
> index notation instead of calculating the pointer address twice
> would resolve this issue. The unneeded local variable oldsize
> can be removed as well.

Can't believe I missed this first two times time through - the patch
is missing your signed-off-by. Just reply with it, and I'll fix it
up on commit. :)

Thanks, Rich!

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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