Mats Petersson
2012-Nov-16 18:36 UTC
[PATCH V3] Correctly return success from IOCTL_PRIVCMD_MMAPBATCH
This is a regression introduced by ceb90fa0 (xen/privcmd: add
PRIVCMD_MMAPBATCH_V2 ioctl). It broke xentrace as it used
xc_map_foreign() instead of xc_map_foreign_bulk().
Most code-paths prefer the MMAPBATCH_V2, so this wasn''t very obvious
that it broke. The return value is set early on to -EINVAL, and if all
goes well, the "set top bits of the MFN''s" never gets called,
so the
return value is still EINVAL when the function gets to the end, causing
the caller to think it went wrong (which it didn''t!)
Now also including Andres "move the ret = -EINVAL into the error handling
path, as this avoids other similar errors in future.
Signed off by: Mats Petersson <mats.petersson@citrix.com>
Acked-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: David Vrabel <david.vrabel@citrix.com>
---
drivers/xen/privcmd.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 8adb9cc..71f5c45 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -361,13 +361,13 @@ static long privcmd_ioctl_mmap_batch(void __user *udata,
int version)
down_write(&mm->mmap_sem);
vma = find_vma(mm, m.addr);
- ret = -EINVAL;
if (!vma ||
vma->vm_ops != &privcmd_vm_ops ||
(m.addr != vma->vm_start) ||
((m.addr + (nr_pages << PAGE_SHIFT)) != vma->vm_end) ||
!privcmd_enforce_singleshot_mapping(vma)) {
up_write(&mm->mmap_sem);
+ ret = -EINVAL;
goto out;
}
@@ -383,12 +383,16 @@ static long privcmd_ioctl_mmap_batch(void __user *udata,
int version)
up_write(&mm->mmap_sem);
- if (state.global_error && (version == 1)) {
- /* Write back errors in second pass. */
- state.user_mfn = (xen_pfn_t *)m.arr;
- state.err = err_array;
- ret = traverse_pages(m.num, sizeof(xen_pfn_t),
- &pagelist, mmap_return_errors_v1, &state);
+ if (version == 1) {
+ if (state.global_error) {
+ /* Write back errors in second pass. */
+ state.user_mfn = (xen_pfn_t *)m.arr;
+ state.err = err_array;
+ ret = traverse_pages(m.num, sizeof(xen_pfn_t),
+ &pagelist, mmap_return_errors_v1, &state);
+ } else
+ ret = 0;
+
} else if (version == 2) {
ret = __copy_to_user(m.err, err_array, m.num * sizeof(int));
if (ret)
--
1.7.9.5
David Vrabel
2012-Nov-19 11:52 UTC
Re: [PATCH V3] Correctly return success from IOCTL_PRIVCMD_MMAPBATCH
On 16/11/12 18:36, Mats Petersson wrote:> This is a regression introduced by ceb90fa0 (xen/privcmd: add > PRIVCMD_MMAPBATCH_V2 ioctl). It broke xentrace as it used > xc_map_foreign() instead of xc_map_foreign_bulk().Konrad, This is a regression introduced in 3.7-rc1. Can you pick this one up for 3.7? Thanks. David> > Most code-paths prefer the MMAPBATCH_V2, so this wasn''t very obvious > that it broke. The return value is set early on to -EINVAL, and if all > goes well, the "set top bits of the MFN''s" never gets called, so the > return value is still EINVAL when the function gets to the end, causing > the caller to think it went wrong (which it didn''t!) > > Now also including Andres "move the ret = -EINVAL into the error handling > path, as this avoids other similar errors in future. > > Signed off by: Mats Petersson <mats.petersson@citrix.com> > Acked-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> > Acked-by: David Vrabel <david.vrabel@citrix.com> > --- > drivers/xen/privcmd.c | 18 +++++++++++------- > 1 file changed, 11 insertions(+), 7 deletions(-) > > diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c > index 8adb9cc..71f5c45 100644 > --- a/drivers/xen/privcmd.c > +++ b/drivers/xen/privcmd.c > @@ -361,13 +361,13 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) > down_write(&mm->mmap_sem); > > vma = find_vma(mm, m.addr); > - ret = -EINVAL; > if (!vma || > vma->vm_ops != &privcmd_vm_ops || > (m.addr != vma->vm_start) || > ((m.addr + (nr_pages << PAGE_SHIFT)) != vma->vm_end) || > !privcmd_enforce_singleshot_mapping(vma)) { > up_write(&mm->mmap_sem); > + ret = -EINVAL; > goto out; > } > > @@ -383,12 +383,16 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) > > up_write(&mm->mmap_sem); > > - if (state.global_error && (version == 1)) { > - /* Write back errors in second pass. */ > - state.user_mfn = (xen_pfn_t *)m.arr; > - state.err = err_array; > - ret = traverse_pages(m.num, sizeof(xen_pfn_t), > - &pagelist, mmap_return_errors_v1, &state); > + if (version == 1) { > + if (state.global_error) { > + /* Write back errors in second pass. */ > + state.user_mfn = (xen_pfn_t *)m.arr; > + state.err = err_array; > + ret = traverse_pages(m.num, sizeof(xen_pfn_t), > + &pagelist, mmap_return_errors_v1, &state); > + } else > + ret = 0; > + > } else if (version == 2) { > ret = __copy_to_user(m.err, err_array, m.num * sizeof(int)); > if (ret)