On Wed, Aug 26, 2015 at 04:57:37PM -0500, Rich Johnston wrote: > Dave, > > On 08/26/2015 04:37 PM, Dave Chinner wrote: > >On Wed, Aug 26, 2015 at 12:36:42PM -0500, rjohnston@xxxxxxx 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. > >> > >>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. > >> > Per your other comment I will add a bounds check after calculating numsegs: > if (numsegs < 0) > return -1; > > The description above will change to: > > 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. Sounds good. Thanks, Rich. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
