On Sun, Feb 05, 2012 at 10:23:44PM +0100, Jesper Juhl wrote: > In xfs_setattr_nonsize(), xfs_trans_alloc() gets its memory from > _xfs_trans_alloc() which gets it from kmem_zone_zalloc() which may > fail and return NULL. So this: > > tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE); > > may result in a NULL 'tp'. > If it does, then the call: > > error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0); > > with a NULL 'tp' will explode, since xfs_trans_reserve() dereferences > its first argument unconditionally. xfs_trans_alloc() can't fail. It will sleep forever until the memory allocation succeeds. There's 35 other places in XFS where this xfs_trans_alloc/ xfs_trans_reserve pattern occurs - none of them check whether tp is null, either. > And if the memory allocation for 'tp' goes well (and thus > xfs_trans_reserve() does not explode) then we may leak the memory > allocated to 'tp' if xfs_trans_reserve() returns error. yes, that's a problem, though will only happen if a filesystem shutdown occurs between the start of the function and that check. > > I believe this patch should fix both issues, but I'm not intimate with > the XFS code at all, so there can easily be something I overlooked or > something that should be done differently than what I did. Only need to fix the leak of tp. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
