From 90fba22b04faf110e70ccd8b3edab7a3ed8df4d4 Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Sun, 24 Apr 2022 11:29:55 +0800 Subject: [PATCH] mm: gup: fix potential pgmap refcnt leak in __gup_device_huge() 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/?id=6401c4eb57f947a49eb144b5b0787cde3318e82e -------------------------------- 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 Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Reviewed-by: John Hubbard Reviewed-by: Claudio Imbrenda Cc: Jan Kara Cc: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds (cherry picked from commit 6401c4eb57f947a49eb144b5b0787cde3318e82e) Signed-off-by: Yue Zou Reviewed-by: Kefeng Wang Signed-off-by: Zheng Zengkai --- 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, -- GitLab