From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, linmiaohe@huawei.com,
linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org,
torvalds@linux-foundation.org, willy@infradead.org
Subject: [patch 18/29] include/linux/sched/mm.h: use rcu_dereference in in_vfork()
Date: Fri, 12 Mar 2021 21:08:03 -0800 [thread overview]
Message-ID: <20210313050803.CFTW-ffYI%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210312210632.9b7d62973d72a56fb13c7a03@linux-foundation.org>
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: include/linux/sched/mm.h: use rcu_dereference in in_vfork()
Fix a sparse warning by using rcu_dereference(). Technically this is a
bug and a sufficiently aggressive compiler could reload the `real_parent'
pointer outside the protection of the rcu lock (and access freed memory),
but I think it's pretty unlikely to happen.
Link: https://lkml.kernel.org/r/20210221194207.1351703-1-willy@infradead.org
Fixes: b18dc5f291c0 ("mm, oom: skip vforked tasks from being selected")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/sched/mm.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/linux/sched/mm.h~mm-use-rcu_dereference-in-in_vfork
+++ a/include/linux/sched/mm.h
@@ -140,7 +140,8 @@ static inline bool in_vfork(struct task_
* another oom-unkillable task does this it should blame itself.
*/
rcu_read_lock();
- ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
+ ret = tsk->vfork_done &&
+ rcu_dereference(tsk->real_parent)->mm == tsk->mm;
rcu_read_unlock();
return ret;
_
next prev parent reply other threads:[~2021-03-13 5:08 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 5:06 incoming Andrew Morton
2021-03-13 5:07 ` [patch 01/29] memblock: fix section mismatch warning Andrew Morton
2021-03-13 5:07 ` [patch 02/29] stop_machine: mark helpers __always_inline Andrew Morton
2021-03-13 5:07 ` [patch 03/29] init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM Andrew Morton
2021-03-13 5:07 ` [patch 04/29] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout Andrew Morton
2021-03-13 5:07 ` [patch 05/29] mm/fork: clear PASID for new mm Andrew Morton
2021-03-13 5:07 ` [patch 06/29] hugetlb: dedup the code to add a new file_region Andrew Morton
2021-03-13 5:07 ` [patch 07/29] hugetlb: break earlier in add_reservation_in_range() when we can Andrew Morton
2021-03-13 5:07 ` [patch 08/29] mm: introduce page_needs_cow_for_dma() for deciding whether cow Andrew Morton
2021-03-13 5:07 ` [patch 09/29] mm: use is_cow_mapping() across tree where proper Andrew Morton
2021-03-13 5:07 ` [patch 10/29] hugetlb: do early cow when page pinned on src mm Andrew Morton
2021-03-13 5:07 ` [patch 11/29] mm/highmem.c: fix zero_user_segments() with start > end Andrew Morton
2021-03-13 5:07 ` [patch 12/29] binfmt_misc: fix possible deadlock in bm_register_write Andrew Morton
2021-03-13 5:07 ` [patch 13/29] MAINTAINERS: exclude uapi directories in API/ABI section Andrew Morton
2021-03-13 5:07 ` [patch 14/29] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP* Andrew Morton
2021-03-13 5:07 ` [patch 15/29] kfence: fix printk format for ptrdiff_t Andrew Morton
2021-03-13 5:07 ` [patch 16/29] kfence, slab: fix cache_alloc_debugcheck_after() for bulk allocations Andrew Morton
2021-03-13 5:08 ` [patch 17/29] kfence: fix reports if constant function prefixes exist Andrew Morton
2021-03-13 5:08 ` Andrew Morton [this message]
2021-03-13 5:08 ` [patch 19/29] mm/madvise: replace ptrace attach requirement for process_madvise Andrew Morton
2021-03-13 5:08 ` [patch 20/29] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC Andrew Morton
2021-03-13 5:08 ` [patch 21/29] kasan: fix KASAN_STACK dependency for HW_TAGS Andrew Morton
2021-03-13 5:08 ` [patch 22/29] mm/userfaultfd: fix memory corruption due to writeprotect Andrew Morton
2021-03-13 5:08 ` [patch 23/29] mm, hwpoison: do not lock page again when me_huge_page() successfully recovers Andrew Morton
2021-03-13 19:23 ` Linus Torvalds
2021-03-14 6:36 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-13 5:08 ` [patch 24/29] ia64: fix ia64_syscall_get_set_arguments() for break-based syscalls Andrew Morton
2021-03-13 5:08 ` [patch 25/29] ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign Andrew Morton
2021-03-13 5:08 ` [patch 26/29] mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument Andrew Morton
2021-03-13 5:08 ` [patch 27/29] mm/memcg: set memcg when splitting page Andrew Morton
2021-03-13 5:08 ` [patch 28/29] zram: fix return value on writeback_store Andrew Morton
2021-03-13 5:08 ` [patch 29/29] zram: fix broken page writeback Andrew Morton
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