On Tue, May 12, 2020 at 01:26:43PM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
The patch below does not apply to the 4.4-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
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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>
There was a context conflict with 441a62780687 ("arm64/hugetlb: Use
macros for contiguous huge page sizes"). I've fixed it and queued the
patch for 4.14 and 4.9.
--
Thanks,
Sasha
