From: Juergen Gross <jgross@suse.com> mainline inclusion from mainline-v6.0-rc3 commit c5deb27895e017a0267de0a20d140ad5fcc55a54 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICG959 CVE: CVE-2022-49989 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The error exit of privcmd_ioctl_dm_op() is calling unlock_pages() potentially with pages being NULL, leading to a NULL dereference. Additionally lock_pages() doesn't check for pin_user_pages_fast() having been completely successful, resulting in potentially not locking all pages into memory. This could result in sporadic failures when using the related memory in user mode. Fix all of that by calling unlock_pages() always with the real number of pinned pages, which will be zero in case pages being NULL, and by checking the number of pages pinned by pin_user_pages_fast() matching the expected number of pages. Cc: <stable@vger.kernel.org> Fixes: ab520be8cd5d ("xen/privcmd: Add IOCTL_PRIVCMD_DM_OP") Reported-by: Rustam Subkhankulov <subkhankulov@ispras.ru> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/20220825141918.3581-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com> Conflicts: drivers/xen/privcmd.c [The "git am" command reports a conflict due to the context of the function definition. There is no conflict where the code is modified, and then manually patched.] Signed-off-by: Cheng Yu <serein.chengyu@huawei.com> --- drivers/xen/privcmd.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index fc9f89a4d2b1..56f2458f012a 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -583,27 +583,30 @@ static int lock_pages( struct privcmd_dm_op_buf kbufs[], unsigned int num, struct page *pages[], unsigned int nr_pages, unsigned int *pinned) { - unsigned int i; + unsigned int i, off = 0; - for (i = 0; i < num; i++) { + for (i = 0; i < num; ) { unsigned int requested; int page_count; requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, - PAGE_SIZE); + PAGE_SIZE) - off; if (requested > nr_pages) return -ENOSPC; page_count = get_user_pages_fast( - (unsigned long) kbufs[i].uptr, + (unsigned long)kbufs[i].uptr + off * PAGE_SIZE, requested, FOLL_WRITE, pages); - if (page_count < 0) - return page_count; + if (page_count <= 0) + return page_count ? : -EFAULT; *pinned += page_count; nr_pages -= page_count; pages += page_count; + + off = (requested == page_count) ? 0 : off + page_count; + i += !off; } return 0; @@ -682,10 +685,8 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) } rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned); - if (rc < 0) { - nr_pages = pinned; + if (rc < 0) goto out; - } for (i = 0; i < kdata.num; i++) { set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr); @@ -697,7 +698,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) xen_preemptible_hcall_end(); out: - unlock_pages(pages, nr_pages); + unlock_pages(pages, pinned); kfree(xbufs); kfree(pages); kfree(kbufs); -- 2.25.1