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Old 07-06-2012, 06:24 PM
Herton Ronaldo Krzesinski
 
Default hugetlb: fix resv_map leak in error path

On Thu, Jul 05, 2012 at 02:40:33PM -0700, Brad Figg wrote:
> From: Dave Hansen <dave@linux.vnet.ibm.com>
>
> CVE-2012-2390
>
> BugLink: http://bugs.launchpad.net/bugs/1004621
>
> When called for anonymous (non-shared) mappings, hugetlb_reserve_pages()
> does a resv_map_alloc(). It depends on code in hugetlbfs's
> vm_ops->close() to release that allocation.
>
> However, in the mmap() failure path, we do a plain unmap_region() without
> the remove_vma() which actually calls vm_ops->close().
>
> This is a decent fix. This leak could get reintroduced if new code (say,
> after hugetlb_reserve_pages() in hugetlbfs_file_mmap()) decides to return
> an error. But, I think it would have to unroll the reservation anyway.
>
> Christoph's test case:
>
> http://marc.info/?l=linux-mm&m=133728900729735
>
> This patch applies to 3.4 and later. A version for earlier kernels is at
> https://lkml.org/lkml/2012/5/22/418.
>
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
> Acked-by: Mel Gorman <mel@csn.ul.ie>
> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Reported-by: Christoph Lameter <cl@linux.com>
> Tested-by: Christoph Lameter <cl@linux.com>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: <stable@vger.kernel.org> [2.6.32+]
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> (cherry picked from commit c50ac050811d6485616a193eb0f37bfbd191cc89)
> Signed-off-by: Brad Figg <brad.figg@canonical.com>
> ---
> mm/hugetlb.c | 28 ++++++++++++++++++++++------
> 1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 20f9240..3d61035 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1772,6 +1772,15 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma)
> kref_get(&reservations->refs);
> }
>
> +static void resv_map_put(struct vm_area_struct *vma)
> +{
> + struct resv_map *reservations = vma_resv_map(vma);
> +
> + if (!reservations)
> + return;
> + kref_put(&reservations->refs, resv_map_release);
> +}
> +
> static void hugetlb_vm_op_close(struct vm_area_struct *vma)
> {
> struct hstate *h = hstate_vma(vma);
> @@ -1788,7 +1797,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
> reserve = (end - start) -
> region_count(&reservations->regions, start, end);
>
> - kref_put(&reservations->refs, resv_map_release);
> + resv_map_put(vma);
>
> if (reserve) {
> hugetlb_acct_memory(h, -reserve);
> @@ -2472,12 +2481,16 @@ int hugetlb_reserve_pages(struct inode *inode,
> set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
> }
>
> - if (chg < 0)
> - return chg;
> + if (chg < 0) {
> + ret = chg;
> + goto out_err;
> + }
>
> /* There must be enough pages in the subpool for the mapping */
> - if (hugepage_subpool_get_pages(spool, chg))
> - return -ENOSPC;
> + if (hugepage_subpool_get_pages(spool, chg)) {
> + ret = -ENOSPC;
> + goto out_err;
> + }
>
> /*
> * Check enough hugepages are available for the reservation.
> @@ -2486,7 +2499,7 @@ int hugetlb_reserve_pages(struct inode *inode,
> ret = hugetlb_acct_memory(h, chg);
> if (ret < 0) {
> hugepage_subpool_put_pages(spool, chg);
> - return ret;
> + goto out_err;
> }
>
> /*
> @@ -2503,6 +2516,9 @@ int hugetlb_reserve_pages(struct inode *inode,
> if (!vma || vma->vm_flags & VM_MAYSHARE)
> region_add(&inode->i_mapping->private_list, from, to);
> return 0;
> +out_err:
> + resv_map_put(vma);
> + return ret;

Looks like we have also have to pick 4523e1458566a0e8ecfaff90f380dd23acc44d27
on top after applying this, to avoid issues here.

> }
>
> void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
> --
> 1.7.9.5
>
>
> --
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>

--
[]'s
Herton

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