On Tue, 12 May 2020 at 16:56, <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 027d0c7101f50cf03aeea9eebf484afd4920c8d3 Mon Sep 17 00:00:00 2001
> From: Mark Rutland <mark.rutland@xxxxxxx>
> Date: Tue, 5 May 2020 13:59:30 +0100
> Subject: [PATCH] arm64: hugetlb: avoid potential NULL dereference
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> 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: 66b3923a1a0f ("arm64: hugetlb: add support for PTE contiguous bit")
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Reported-by: Kyrill Tkachov <kyrylo.tkachov@xxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.5.x-
> Cc: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index bbeb6a5a6ba6..0be3355e3499 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -230,6 +230,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
> ptep = (pte_t *)pudp;
> } else if (sz == (CONT_PTE_SIZE)) {
> pmdp = pmd_alloc(mm, pudp, addr);
> + if (!pmdp)
> + return NULL;
>
> WARN_ON(addr & (sz - 1));
> /*
As per the subject this patch failed to apply on 4.14
FYI,
on stable-rc 4.14 branch arm64 architecture build failed.
# make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=arm64
CROSS_COMPILE=aarch64-linux-gnu- HOSTCC=gcc CC="sccache
aarch64-linux-gnu-gcc" O=build Image
70 #
71 ../arch/arm64/mm/hugetlbpage.c: In function ‘huge_pte_alloc’:
72 ../arch/arm64/mm/hugetlbpage.c:223:8: error: ‘pmdp’ undeclared
(first use in this function); did you mean ‘pmd’?
73 223 | if (!pmdp)
74 | ^~~~
75 | pmd
76 ../arch/arm64/mm/hugetlbpage.c:223:8: note: each undeclared
identifier is reported only once for each function it appears in
77 make[2]: *** [../scripts/Makefile.build:326:
arch/arm64/mm/hugetlbpage.o] Error 1
ref:
https://gitlab.com/Linaro/lkft/kernel-runs/-/jobs/550145375
--
Linaro LKFT
https://lkft.linaro.org
