On Wed, May 13, 2020 at 01:21:20PM +0200, Greg Kroah-Hartman wrote:
On Wed, May 13, 2020 at 11:35:45AM +0100, Will Deacon wrote:
[+Sasha, as I think he did the backport]
On Wed, May 13, 2020 at 04:02:09PM +0530, Naresh Kamboju wrote:
On Tue, 12 May 2020 at 16:56, gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 4.9-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@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 027d0c7101f50cf03aeea9eebf484afd4920c8d3 Mon Sep 17 00:00:00 2001 From: Mark Rutland mark.rutland@arm.com 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@arm.com Reported-by: Kyrill Tkachov kyrylo.tkachov@arm.com Cc: stable@vger.kernel.org # 4.5.x- Cc: Will Deacon will@kernel.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com
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)); /*on stable-rc 4.9 branch arm64 architecture build failed.
CC arch/arm64/mm/hugetlbpage.o arch/arm64/mm/hugetlbpage.c: In function 'huge_pte_alloc': arch/arm64/mm/hugetlbpage.c:106:8: error: 'pmdp' undeclared (first use in this function); did you mean 'pmd'? if (!pmdp) ^~~~ pmd arch/arm64/mm/hugetlbpage.c:106:8: note: each undeclared identifier is reported only once for each function it appears in scripts/Makefile.build:304: recipe for target 'arch/arm64/mm/hugetlbpage.o' failed
ref: https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-4.9/DI...
Now dropped from 4.9 as well.
'pmdp' -> 'pmd' Argh :(