On 10/13/11 1:50 PM, Alex Elder wrote:
> The libxfs code uses radix tree routines to manage a mount
> point's m_perag_tree. But the radix tree routines assume
> that radix_tree_init() has been called to initialize the
> height_to_maxindex[] global array, and this was not being
> done.
>
> This showed up when running mkfs.xfs on an ia64 system. Since
> it wasn't initialized, the array was filled with zeroes. The
> first time radix_tree_extend() got called (with index 0), the
> height would be set to 1 and all would seem fine.
>
> The *second* time it got called (with index 1) a problem would
> arise--though we were apparently "lucky" enough for it not to
> matter. The following loop would simply reference invalid slots
> beyond the end of the array until it happened upon one that was
> non-zero. (I've expanded the function radix_tree_maxindex() here.)
>
> /* Figure out what the height should be. */
> height = root->height + 1;
> while (index > height_to_maxindex[height])
> height++;
>
> As an example, this looped 1937 times before it found a non-zere
> value that would cause it to break out of the loop.
>
> Even that *seemed* to be OK. But at the end of mkfs.xfs, when
> it calls libxfs_umount(), non-initialized "slots" are dereferenced
> and we hit a fault.
>
> Wow.
>
> Signed-off-by: Alex Elder <aelder@xxxxxxx>
I suppose if we have an init function we may as well call it at
least once. ;)
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> libxfs/init.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> Index: b/libxfs/init.c
> ===================================================================
> --- a/libxfs/init.c
> +++ b/libxfs/init.c
> @@ -249,6 +249,8 @@ libxfs_init(libxfs_init_t *a)
> fd = -1;
> flags = (a->isreadonly | a->isdirect);
>
> + radix_tree_init();
> +
> if (a->volname) {
> if(!check_open(a->volname,flags,&rawfile,&blockfile))
> goto done;
>
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs
>
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
