From b3029c71380e3e659d0646dffc7ce60f2322bfc5 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Sat, 28 May 2022 17:57:21 +0800 Subject: [PATCH] slub: add back check for free nonslab objects mainline inclusion from mainline-v5.16-rc1 commit d0fe47c64152a63ceed4b9f29ac56371407fa7b4 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I57LS2 CVE: NA backport: openEuler-22.03-LTS -------------------------------- After commit f227f0faf63b ("slub: fix unreclaimable slab stat for bulk free"), the check for free nonslab page is replaced by VM_BUG_ON_PAGE, which only check with CONFIG_DEBUG_VM enabled, but this config may impact performance, so it only for debug. Commit 0937502af7c9 ("slub: Add check for kfree() of non slab objects.") add the ability, which should be needed in any configs to catch the invalid free, they even could be potential issue, eg, memory corruption, use after free and double free, so replace VM_BUG_ON_PAGE to WARN_ON_ONCE, add object address printing to help use to debug the issue. Link: https://lkml.kernel.org/r/20210930070214.61499-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Cc: Matthew Wilcox Cc: Shakeel Butt Cc: Vlastimil Babka Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rienjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ma Wupeng Reviewed-by: Kefeng Wang Signed-off-by: Zheng Zengkai --- mm/slub.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 7a7b0bf82b8e..98452815a066 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3209,7 +3209,9 @@ static inline void free_nonslab_page(struct page *page, void *object) { unsigned int order = compound_order(page); - VM_BUG_ON_PAGE(!PageCompound(page), page); + if (WARN_ON_ONCE(!PageCompound(page))) + pr_warn_once("object pointer: 0x%p\n", object); + kfree_hook(object); mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order)); __free_pages(page, order); -- GitLab