From: Peter Zijlstra <peterz@infradead.org>
To: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH][next] x86/mm/pgtable: Fix Wstringop-overflow warnings
Date: Fri, 1 Apr 2022 15:12:22 +0200 [thread overview]
Message-ID: <Ykb6Nv80LJomLDsO@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20220401005834.GA182932@embeddedor>
On Thu, Mar 31, 2022 at 07:58:34PM -0500, Gustavo A. R. Silva wrote:
> Fix the following -Wstringop-overflow warnings when building with GCC-11:
>
> .arch/x86/mm/pgtable.c: In function ‘pgd_alloc’:
> arch/x86/mm/pgtable.c:437:13: warning: ‘preallocate_pmds.constprop’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]
> 437 | if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0)
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:437:13: note: referencing argument 2 of type ‘pmd_t **’
> arch/x86/mm/pgtable.c:225:12: note: in a call to function ‘preallocate_pmds.constprop’
> 225 | static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
> | ^~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:440:13: warning: ‘preallocate_pmds.constprop’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]
> 440 | if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0)
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:440:13: note: referencing argument 2 of type ‘pmd_t **’
> arch/x86/mm/pgtable.c:225:12: note: in a call to function ‘preallocate_pmds.constprop’
> 225 | static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
> | ^~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:462:9: warning: ‘free_pmds.constprop’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]
> 462 | free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:462:9: note: referencing argument 2 of type ‘pmd_t **’
> arch/x86/mm/pgtable.c:213:13: note: in a call to function ‘free_pmds.constprop’
> 213 | static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
> | ^~~~~~~~~
> arch/x86/mm/pgtable.c:455:9: warning: ‘pgd_prepopulate_user_pmd’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]
> 455 | pgd_prepopulate_user_pmd(mm, pgd, u_pmds);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:455:9: note: referencing argument 3 of type ‘pmd_t **’
> arch/x86/mm/pgtable.c:320:13: note: in a call to function ‘pgd_prepopulate_user_pmd’
> 320 | static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
> | ^~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:464:9: warning: ‘free_pmds.constprop’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=]
> 464 | free_pmds(mm, pmds, PREALLOCATED_PMDS);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> arch/x86/mm/pgtable.c:464:9: note: referencing argument 2 of type ‘pmd_t **’
> arch/x86/mm/pgtable.c:213:13: note: in a call to function ‘free_pmds.constprop’
> 213 | static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
> | ^~~~~~~~~
>
> by using pointer notation instead of array notation as a workaround for
> the above GCC warnings.
'Workaround' implies the warning is on crack...
> This helps with the ongoing efforts to globally enable
> -Wstringop-overflow.
which puts to question this endeavour, why are you wanting to have this
if its crap?
prev parent reply other threads:[~2022-04-01 13:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-01 0:58 [PATCH][next] x86/mm/pgtable: Fix Wstringop-overflow warnings Gustavo A. R. Silva
2022-04-01 13:12 ` Peter Zijlstra [this message]
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