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authorSouptick Joarder <jrdr.linux@gmail.com>2020-07-12 06:39:53 +0300
committerJuergen Gross <jgross@suse.com>2020-08-03 08:41:25 +0300
commite398fb4bdf522abdeb8ddb61235bbf66065fc105 (patch)
tree08b42848e791b9d665f7928eae9c347c8034dc98 /drivers/xen/privcmd.c
parentbcf876870b95592b52519ed4aafcf9d95999bc9c (diff)
downloadlinux-e398fb4bdf522abdeb8ddb61235bbf66065fc105.tar.xz
xen/privcmd: Corrected error handling path
Previously, if lock_pages() end up partially mapping pages, it used to return -ERRNO due to which unlock_pages() have to go through each pages[i] till *nr_pages* to validate them. This can be avoided by passing correct number of partially mapped pages & -ERRNO separately, while returning from lock_pages() due to error. With this fix unlock_pages() doesn't need to validate pages[i] till *nr_pages* for error scenario and few condition checks can be ignored. Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Paul Durrant <paul@xen.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Paul Durrant <xadimgnik@gmail.com> Link: https://lore.kernel.org/r/1594525195-28345-2-git-send-email-jrdr.linux@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen/privcmd.c')
-rw-r--r--drivers/xen/privcmd.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index a250d118144a..a9b2baa2c7be 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -580,13 +580,13 @@ out_unlock:
static int lock_pages(
struct privcmd_dm_op_buf kbufs[], unsigned int num,
- struct page *pages[], unsigned int nr_pages)
+ struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
{
unsigned int i;
for (i = 0; i < num; i++) {
unsigned int requested;
- int pinned;
+ int page_count;
requested = DIV_ROUND_UP(
offset_in_page(kbufs[i].uptr) + kbufs[i].size,
@@ -594,14 +594,15 @@ static int lock_pages(
if (requested > nr_pages)
return -ENOSPC;
- pinned = get_user_pages_fast(
+ page_count = get_user_pages_fast(
(unsigned long) kbufs[i].uptr,
requested, FOLL_WRITE, pages);
- if (pinned < 0)
- return pinned;
+ if (page_count < 0)
+ return page_count;
- nr_pages -= pinned;
- pages += pinned;
+ *pinned += page_count;
+ nr_pages -= page_count;
+ pages += page_count;
}
return 0;
@@ -611,13 +612,8 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
{
unsigned int i;
- if (!pages)
- return;
-
- for (i = 0; i < nr_pages; i++) {
- if (pages[i])
- put_page(pages[i]);
- }
+ for (i = 0; i < nr_pages; i++)
+ put_page(pages[i]);
}
static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
@@ -630,6 +626,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
struct xen_dm_op_buf *xbufs = NULL;
unsigned int i;
long rc;
+ unsigned int pinned = 0;
if (copy_from_user(&kdata, udata, sizeof(kdata)))
return -EFAULT;
@@ -683,9 +680,11 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
goto out;
}
- rc = lock_pages(kbufs, kdata.num, pages, nr_pages);
- if (rc)
+ rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
+ if (rc < 0) {
+ nr_pages = pinned;
goto out;
+ }
for (i = 0; i < kdata.num; i++) {
set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);