From: Ingo Molnar <mingo@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Song Liu <songliubraving@fb.com>,
Joerg Roedel <jroedel@suse.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@surriel.com>
Subject: Re: [patch V3 1/2] x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable()
Date: Thu, 29 Aug 2019 01:22:33 +0200 [thread overview]
Message-ID: <20190828232233.GA99597@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1908282352470.1938@nanos.tec.linutronix.de>
* Thomas Gleixner <tglx@linutronix.de> wrote:
> From: Song Liu <songliubraving@fb.com>
>
> pti_clone_pmds() assumes that the supplied address is either:
>
> - properly PUD/PMD aligned
> or
> - the address is actually mapped which means that independently
> of the mapping level (PUD/PMD/PTE) the next higher mapping
> exists.
>
> If that's not the case the unaligned address can be incremented by PUD or
> PMD size incorrectly. All callers supply mapped and/or aligned addresses,
> but for the sake of robustness it's better to handle that case properly and
> to emit a warning.
>
> [ tglx: Rewrote changelog and added WARN_ON_ONCE() ]
>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V2: Negate P[UM]D_MASK for checking whether the offset part is 0
> V3: Fix changelog
> ---
> arch/x86/mm/pti.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> --- a/arch/x86/mm/pti.c
> +++ b/arch/x86/mm/pti.c
> @@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, u
>
> pud = pud_offset(p4d, addr);
> if (pud_none(*pud)) {
> - addr += PUD_SIZE;
> + WARN_ON_ONCE(addr & ~PUD_MASK);
> + addr = round_up(addr + 1, PUD_SIZE);
> continue;
> }
>
> pmd = pmd_offset(pud, addr);
> if (pmd_none(*pmd)) {
> - addr += PMD_SIZE;
> + WARN_ON_ONCE(addr & ~PMD_MASK);
> + addr = round_up(addr + 1, PMD_SIZE);
> continue;
> }
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
next prev parent reply other threads:[~2019-08-28 23:22 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-28 14:24 [patch 0/2] x86/mm/pti: Robustness updates Thomas Gleixner
2019-08-28 14:24 ` [patch 1/2] x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable() Thomas Gleixner
2019-08-28 15:46 ` Dave Hansen
2019-08-28 15:51 ` Thomas Gleixner
2019-08-28 17:58 ` Song Liu
2019-08-28 20:05 ` Thomas Gleixner
2019-08-28 20:32 ` Song Liu
2019-08-28 22:31 ` [PATCH] x86/mm/cpa: Prevent large page split when ftrace flips RW on kernel text Thomas Gleixner
2019-08-28 23:03 ` Song Liu
2019-08-29 13:01 ` Peter Zijlstra
2019-08-29 18:55 ` [tip: x86/urgent] " tip-bot2 for Thomas Gleixner
2019-08-28 18:58 ` [patch 1/2] x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable() Ingo Molnar
2019-08-28 19:45 ` Thomas Gleixner
2019-08-28 20:54 ` [patch V2 " Thomas Gleixner
2019-08-28 21:52 ` Thomas Gleixner
2019-08-28 21:54 ` [patch V3 " Thomas Gleixner
2019-08-28 23:22 ` Ingo Molnar [this message]
2019-08-29 19:02 ` [tip: x86/pti] " tip-bot2 for Song Liu
2019-08-30 10:24 ` [patch V3 1/2] " Joerg Roedel
2019-08-28 14:24 ` [patch 2/2] x86/mm/pti: Do not invoke PTI functions when PTI is disabled Thomas Gleixner
2019-08-28 15:47 ` Dave Hansen
2019-08-28 17:49 ` Song Liu
2019-08-28 19:00 ` Ingo Molnar
2019-08-29 19:02 ` [tip: x86/pti] " tip-bot2 for Thomas Gleixner
2019-08-30 10:25 ` [patch 2/2] " Joerg Roedel
2019-08-28 16:03 ` [patch 0/2] x86/mm/pti: Robustness updates Peter Zijlstra
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