From: Andrew Morton <akpm@linux-foundation.org>
To: Liam Ni <zhiguangni01@gmail.com>
Cc: dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, hpa@zytor.com, rppt@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm/sparse:avoid null pointer access in memory_present()
Date: Fri, 16 Jun 2023 22:44:07 -0700 [thread overview]
Message-ID: <20230616224407.863c74a3dc9d4f1427802f91@linux-foundation.org> (raw)
In-Reply-To: <20230617044036.3985524-1-zhiguangni01@gmail.com>
On Sat, 17 Jun 2023 14:40:36 +1000 Liam Ni <zhiguangni01@gmail.com> wrote:
> __nr_to_section() may return a null pointer,
> before accessing the member variable section_mem_map,
> we should first determine whether it is a null pointer.
>
> ...
>
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -258,7 +258,7 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
> set_section_nid(section, nid);
>
> ms = __nr_to_section(section);
> - if (!ms->section_mem_map) {
> + if (ms && !ms->section_mem_map) {
> ms->section_mem_map = sparse_encode_early_nid(nid) |
> SECTION_IS_ONLINE;
> __section_mark_present(ms, section);
I'm suspecting that if __nr_to_section() returns NULL here, we should
just panic. But a null-deref gives the same information, so why change
things?
next prev parent reply other threads:[~2023-06-17 5:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-17 4:40 Liam Ni
2023-06-17 5:44 ` Andrew Morton [this message]
2023-06-17 6:17 ` Liam Ni
2023-06-17 7:00 ` Mike Rapoport
2023-06-17 8:59 ` Liam Ni
2023-06-18 7:16 ` Mike Rapoport
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