diff options
| author | Souptick Joarder <jrdr.linux@gmail.com> | 2020-07-12 09:09:53 +0530 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2020-08-03 07:41:25 +0200 |
| commit | e398fb4bdf522abdeb8ddb61235bbf66065fc105 (patch) | |
| tree | 08b42848e791b9d665f7928eae9c347c8034dc98 /drivers/xen | |
| parent | bcf876870b95592b52519ed4aafcf9d95999bc9c (diff) | |
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')
| -rw-r--r-- | drivers/xen/privcmd.c | 31 |
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); |