From: Thomas Garnier <thgarnie@google.com> To: "Mika Penttilä" <mika.penttila@nextfour.com> Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@suse.de>, Joerg Roedel <jroedel@suse.de>, Dave Young <dyoung@redhat.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Lv Zheng <lv.zheng@intel.com>, Baoquan He <bhe@redhat.com>, Dave Hansen <dave.hansen@linux.intel.com>, Mark Salter <msalter@redhat.com>, Aleksey Makarov <aleksey.makarov@linaro.org>, Kees Cook <keescook@chromium.org>, Andrew Morton <akpm@linux-foundation.org>, Christian Borntraeger <borntraeger@de.ibm.com>, Fabian Frederick <fabf@skynet.be>, Toshi Kani <toshi.kani@hp.com>, Dan Williams <dan.j.williams@intel.com>, "the arch/x86 maintainers" <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Kernel Hardening <kernel-hardening@lists.openwall.com> Subject: Re: [PATCH v1 2/2] x86/KASLR: Increase BRK pages for KASLR memory randomization Date: Tue, 9 Aug 2016 07:47:21 -0700 [thread overview] Message-ID: <CAJcbSZFS4Ddt5=QuW+J_p2V4=50VppAgVdydXEjbsTX_e+q7Sg@mail.gmail.com> (raw) In-Reply-To: <68119f42-cb1b-fd3e-3820-7cf235e607e5@nextfour.com> On Mon, Aug 8, 2016 at 10:16 PM, Mika Penttilä <mika.penttila@nextfour.com> wrote: > On 08/08/2016 09:40 PM, Thomas Garnier wrote: >> Default implementation expects 6 pages maximum are needed for low page >> allocations. If KASLR memory randomization is enabled, the worse case >> of e820 layout would require 12 pages (no large pages). It is due to the >> PUD level randomization and the variable e820 memory layout. >> >> This bug was found while doing extensive testing of KASLR memory >> randomization on different type of hardware. >> >> Signed-off-by: Thomas Garnier <thgarnie@google.com> >> --- >> Based on next-20160805 >> --- >> arch/x86/mm/init.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c >> index 6209289..3a27e6a 100644 >> --- a/arch/x86/mm/init.c >> +++ b/arch/x86/mm/init.c >> @@ -130,6 +130,14 @@ void __init early_alloc_pgt_buf(void) >> unsigned long tables = INIT_PGT_BUF_SIZE; >> phys_addr_t base; >> >> + /* >> + * Depending on the machine e860 memory layout and the PUD alignement. >> + * We may need twice more pages when KASLR memoy randomization is >> + * enabled. >> + */ >> + if (IS_ENABLED(CONFIG_RANDOMIZE_MEMORY)) >> + tables *= 2; >> + >> base = __pa(extend_brk(tables, PAGE_SIZE)); >> >> pgt_buf_start = base >> PAGE_SHIFT; >> > > You should increase the reserve also : > RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); Yes, that's right. I will resend v2 changing INIT_PGD_BUF_SIZE. > > > --Mika >
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Garnier <thgarnie@google.com> To: "Mika Penttilä" <mika.penttila@nextfour.com> Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@suse.de>, Joerg Roedel <jroedel@suse.de>, Dave Young <dyoung@redhat.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Lv Zheng <lv.zheng@intel.com>, Baoquan He <bhe@redhat.com>, Dave Hansen <dave.hansen@linux.intel.com>, Mark Salter <msalter@redhat.com>, Aleksey Makarov <aleksey.makarov@linaro.org>, Kees Cook <keescook@chromium.org>, Andrew Morton <akpm@linux-foundation.org>, Christian Borntraeger <borntraeger@de.ibm.com>, Fabian Frederick <fabf@skynet.be>, Toshi Kani <toshi.kani@hp.com>, Dan Williams <dan.j.williams@intel.com>, the arch/x86 maintainers <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Kernel Hardening <kernel-hardening@lists.openwall.com> Subject: [kernel-hardening] Re: [PATCH v1 2/2] x86/KASLR: Increase BRK pages for KASLR memory randomization Date: Tue, 9 Aug 2016 07:47:21 -0700 [thread overview] Message-ID: <CAJcbSZFS4Ddt5=QuW+J_p2V4=50VppAgVdydXEjbsTX_e+q7Sg@mail.gmail.com> (raw) In-Reply-To: <68119f42-cb1b-fd3e-3820-7cf235e607e5@nextfour.com> On Mon, Aug 8, 2016 at 10:16 PM, Mika Penttilä <mika.penttila@nextfour.com> wrote: > On 08/08/2016 09:40 PM, Thomas Garnier wrote: >> Default implementation expects 6 pages maximum are needed for low page >> allocations. If KASLR memory randomization is enabled, the worse case >> of e820 layout would require 12 pages (no large pages). It is due to the >> PUD level randomization and the variable e820 memory layout. >> >> This bug was found while doing extensive testing of KASLR memory >> randomization on different type of hardware. >> >> Signed-off-by: Thomas Garnier <thgarnie@google.com> >> --- >> Based on next-20160805 >> --- >> arch/x86/mm/init.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c >> index 6209289..3a27e6a 100644 >> --- a/arch/x86/mm/init.c >> +++ b/arch/x86/mm/init.c >> @@ -130,6 +130,14 @@ void __init early_alloc_pgt_buf(void) >> unsigned long tables = INIT_PGT_BUF_SIZE; >> phys_addr_t base; >> >> + /* >> + * Depending on the machine e860 memory layout and the PUD alignement. >> + * We may need twice more pages when KASLR memoy randomization is >> + * enabled. >> + */ >> + if (IS_ENABLED(CONFIG_RANDOMIZE_MEMORY)) >> + tables *= 2; >> + >> base = __pa(extend_brk(tables, PAGE_SIZE)); >> >> pgt_buf_start = base >> PAGE_SHIFT; >> > > You should increase the reserve also : > RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); Yes, that's right. I will resend v2 changing INIT_PGD_BUF_SIZE. > > > --Mika >
next prev parent reply other threads:[~2016-08-09 14:53 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-08-08 18:40 [PATCH v1 1/2] x86/KASLR: Fix physical memory calculation on KASLR memory randomization Thomas Garnier 2016-08-08 18:40 ` [kernel-hardening] " Thomas Garnier 2016-08-08 18:40 ` [PATCH v1 2/2] x86/KASLR: Increase BRK pages for " Thomas Garnier 2016-08-08 18:40 ` [kernel-hardening] " Thomas Garnier 2016-08-09 4:01 ` Borislav Petkov 2016-08-09 4:01 ` [kernel-hardening] " Borislav Petkov 2016-08-09 4:14 ` H. Peter Anvin 2016-08-09 4:14 ` [kernel-hardening] " H. Peter Anvin 2016-08-09 5:16 ` Mika Penttilä 2016-08-09 5:16 ` [kernel-hardening] " Mika Penttilä 2016-08-09 14:47 ` Thomas Garnier [this message] 2016-08-09 14:47 ` Thomas Garnier 2016-08-09 15:07 ` [lkp] [x86/KASLR] 20067c4c13: kernel BUG at arch/x86/mm/physaddr.c:26! kernel test robot 2016-08-09 15:07 ` [kernel-hardening] " kernel test robot 2016-08-09 16:00 ` [PATCH v1 1/2] x86/KASLR: Fix physical memory calculation on KASLR memory randomization Thomas Garnier 2016-08-09 16:00 ` [kernel-hardening] " Thomas Garnier 2016-08-09 16:03 ` Joerg Roedel 2016-08-09 16:03 ` [kernel-hardening] " Joerg Roedel 2016-08-09 16:30 ` Thomas Garnier 2016-08-09 16:30 ` [kernel-hardening] " Thomas Garnier
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