From: Miaohe Lin <linmiaohe@huawei.com> mainline inclusion from mainline-v5.15-rc1 commit 6401c4eb57f947a49eb144b5b0787cde3318e82e category: bugfix bugzilla: 180689, https://gitee.com/openeuler/kernel/issues/I53CMX CVE: NA backport: openEuler-22.03-LTS Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When failed to try_grab_page, put_dev_pagemap() is missed. So pgmap refcnt will leak in this case. Also we remove the check for pgmap against NULL as it's also checked inside the put_dev_pagemap(). [akpm@linux-foundation.org: simplify, cleanup] [akpm@linux-foundation.org: fix return value] Link: https://lkml.kernel.org/r/20210807093620.21347-5-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit 6401c4eb57f947a49eb144b5b0787cde3318e82e) Signed-off-by: Yue Zou <zouyue3@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- mm/gup.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index ee9c2c39c299..4e9945299fe5 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2319,6 +2319,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, { int nr_start = *nr; struct dev_pagemap *pgmap = NULL; + int ret = 1; do { struct page *page = pfn_to_page(pfn); @@ -2326,21 +2327,22 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, pgmap = get_dev_pagemap(pfn, pgmap); if (unlikely(!pgmap)) { undo_dev_pagemap(nr, nr_start, flags, pages); - return 0; + ret = 0; + break; } SetPageReferenced(page); pages[*nr] = page; if (unlikely(!try_grab_page(page, flags))) { undo_dev_pagemap(nr, nr_start, flags, pages); - return 0; + ret = 0; + break; } (*nr)++; pfn++; } while (addr += PAGE_SIZE, addr != end); - if (pgmap) - put_dev_pagemap(pgmap); - return 1; + put_dev_pagemap(pgmap); + return ret; } static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, -- 2.20.1