From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Matthew Whitehead <tedheadster@gmail.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 4.8 19/37] x86/traps: Ignore high word of regs->cs in early_fixup_exception()
Date: Wed, 30 Nov 2016 10:29:56 +0100 [thread overview]
Message-ID: <20161130092730.664938401@linuxfoundation.org> (raw)
In-Reply-To: <20161130092729.623248210@linuxfoundation.org>
4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Andy Lutomirski <luto@kernel.org>
commit fc0e81b2bea0ebceb71889b61d2240856141c9ee upstream.
On the 80486 DX, it seems that some exceptions may leave garbage in
the high bits of CS. This causes sporadic failures in which
early_fixup_exception() refuses to fix up an exception.
As far as I can tell, this has been buggy for a long time, but the
problem seems to have been exacerbated by commits:
1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
e1bfc11c5a6f ("x86/init: Fix cr4_init_shadow() on CR4-less machines")
This appears to have broken for as long as we've had early
exception handling.
[ Note to stable maintainers: This patch is needed all the way back to 3.4,
but it will only apply to 4.6 and up, as it depends on commit:
0e861fbb5bda ("x86/head: Move early exception panic code into early_fixup_exception()")
If you want to backport to kernels before 4.6, please don't backport the
prerequisites (there was a big chain of them that rewrote a lot of the
early exception machinery); instead, ask me and I can send you a one-liner
that will apply. ]
Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4c5023a3fa2e ("x86-32: Handle exception table entries during early boot")
Link: http://lkml.kernel.org/r/cb32c69920e58a1a58e7b5cad975038a69c0ce7d.1479609510.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/mm/extable.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -135,7 +135,12 @@ void __init early_fixup_exception(struct
if (early_recursion_flag > 2)
goto halt_loop;
- if (regs->cs != __KERNEL_CS)
+ /*
+ * Old CPUs leave the high bits of CS on the stack
+ * undefined. I'm not sure which CPUs do this, but at least
+ * the 486 DX works this way.
+ */
+ if ((regs->cs & 0xFFFF) != __KERNEL_CS)
goto fail;
/*
next prev parent reply other threads:[~2016-11-30 9:57 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20161130093010epcas2p3047cf63814e74dfcc79f43d37b446ae0@epcas2p3.samsung.com>
2016-11-30 9:29 ` [PATCH 4.8 00/37] 4.8.12-stable review Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 07/37] usb: chipidea: move the lock initialization to core file Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 08/37] USB: serial: cp210x: add ID for the Zone DPMX Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 09/37] USB: serial: ftdi_sio: add support for TI CC3200 LaunchPad Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 10/37] Fix USB CB/CBI storage devices with CONFIG_VMAP_STACK=y Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 11/37] scsi: mpt3sas: Fix secure erase premature termination Greg Kroah-Hartman
2016-11-30 16:49 ` Martin K. Petersen
2016-12-01 7:10 ` Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 12/37] tile: avoid using clocksource_cyc2ns with absolute cycle count Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 13/37] cfg80211: limit scan results cache size Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 15/37] drm/radeon: fix power state when port pm is unavailable (v2) Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 16/37] apparmor: fix change_hat not finding hat after policy replacement Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 17/37] NFSv4.x: hide array-bounds warning Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 18/37] x86/fpu: Fix invalid FPU ptrace state after execve() Greg Kroah-Hartman
2016-11-30 9:29 ` Greg Kroah-Hartman [this message]
2016-11-30 9:29 ` [PATCH 4.8 20/37] perf/core: Fix address filter parser Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 21/37] perf/x86/intel: Cure bogus unwind from PEBS entries Greg Kroah-Hartman
2016-11-30 9:29 ` [PATCH 4.8 22/37] thermal/powerclamp: add back module device table Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 23/37] parisc: Fix races in parisc_setup_cache_timing() Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 24/37] parisc: Switch to generic sched_clock implementation Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 25/37] parisc: Fix race in pci-dma.c Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 26/37] parisc: Also flush data TLB in flush_icache_page_asm Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 27/37] mmc: sdhci-of-esdhc: fixup PRESENT_STATE read Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 28/37] mpi: Fix NULL ptr dereference in mpi_powm() [ver #3] Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 29/37] X.509: Fix double free in x509_cert_parse() " Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 30/37] xc2028: Fix use-after-free bug properly Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 31/37] device-dax: check devm_nsio_enable() return value Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 32/37] device-dax: fail all private mapping attempts Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 33/37] powerpc: Set missing wakeup bit in LPCR on POWER9 Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 34/37] powerpc/mm: Fixup kernel read only mapping Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 35/37] powerpc/boot: Fix the early OPAL console wrappers Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 36/37] can: bcm: fix support for CAN FD frames Greg Kroah-Hartman
2016-11-30 9:30 ` [PATCH 4.8 37/37] mm, oom: stop pre-mature high-order OOM killer invocations Greg Kroah-Hartman
[not found] ` <20161130092730.460938123@linuxfoundation.org>
2016-11-30 10:51 ` [PATCH 4.8 14/37] drm/amdgpu: fix power state when port pm is unavailable Peter Wu
2016-11-30 11:53 ` Greg Kroah-Hartman
2016-12-05 0:11 ` Peter Wu
2016-12-05 14:46 ` Greg Kroah-Hartman
2016-11-30 16:04 ` [PATCH 4.8 00/37] 4.8.12-stable review Shuah Khan
2016-12-01 7:14 ` Greg Kroah-Hartman
2016-11-30 23:34 ` Guenter Roeck
2016-12-01 7:15 ` Greg Kroah-Hartman
[not found] ` <583ed167.6602c20a.c3129.a6b8@mx.google.com>
[not found] ` <m2oa0wkjlk.fsf@baylibre.com>
2016-12-01 7:11 ` Greg Kroah-Hartman
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