From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: hugetlb: avoid potential NULL dereference
Date: Wed, 6 May 2020 11:18:13 +0100 [thread overview]
Message-ID: <20200506101807.GB2878@gaia> (raw)
In-Reply-To: <20200505125930.26901-1-mark.rutland@arm.com>
On Tue, May 05, 2020 at 01:59:30PM +0100, Mark Rutland wrote:
> The static analyzer in GCC 10 spotted that in huge_pte_alloc() we may
> pass a NULL pmdp into pte_alloc_map() when pmd_alloc() returns NULL:
>
> | CC arch/arm64/mm/pageattr.o
> | CC arch/arm64/mm/hugetlbpage.o
> | from arch/arm64/mm/hugetlbpage.c:10:
> | arch/arm64/mm/hugetlbpage.c: In function ‘huge_pte_alloc’:
> | ./arch/arm64/include/asm/pgtable-types.h:28:24: warning: dereference of NULL ‘pmdp’ [CWE-690] [-Wanalyzer-null-dereference]
> | ./arch/arm64/include/asm/pgtable.h:436:26: note: in expansion of macro ‘pmd_val’
> | arch/arm64/mm/hugetlbpage.c:242:10: note: in expansion of macro ‘pte_alloc_map’
> | |arch/arm64/mm/hugetlbpage.c:232:10:
> | |./arch/arm64/include/asm/pgtable-types.h:28:24:
> | ./arch/arm64/include/asm/pgtable.h:436:26: note: in expansion of macro ‘pmd_val’
> | arch/arm64/mm/hugetlbpage.c:242:10: note: in expansion of macro ‘pte_alloc_map’
>
> This can only occur when the kernel cannot allocate a page, and so is
> unlikely to happen in practice before other systems start failing.
>
> We can avoid this by bailing out if pmd_alloc() fails, as we do earlier
> in the function if pud_alloc() fails.
>
> Fixes: 66b3923a1a0f77a5 ("arm64: hugetlb: add support for PTE contiguous bit)"
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Reported-by: Kyrill Tkachov <kyrylo.tkachov@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
Queued for 5.7-rc5. Thanks.
--
Catalin
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prev parent reply other threads:[~2020-05-06 10:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 12:59 [PATCH] arm64: hugetlb: avoid potential NULL dereference Mark Rutland
[not found] ` <CANW9uyt4LorH7cZ+qj51T+yiHwLB+V8d=GjR=yae4APUwyQo+w@mail.gmail.com>
2020-05-05 14:31 ` Mark Rutland
2020-05-06 2:00 ` Itaru Kitayama
2020-05-06 10:18 ` Catalin Marinas [this message]
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