From: Willy Tarreau <w@1wt.eu>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
Ben Hutchings <ben@decadent.org.uk>, Willy Tarreau <w@1wt.eu>
Subject: [ 05/25] x86-32, espfix: Remove filter for espfix32 due to race
Date: Sat, 06 Dec 2014 18:41:53 +0100 [thread overview]
Message-ID: <20141206174148.631937314@1wt.eu> (raw)
In-Reply-To: <2a26e912d2438674771c36169c190830@local>
2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
From: "H. Peter Anvin" <hpa@linux.intel.com>
commit 246f2d2ee1d715e1077fc47d61c394569c8ee692 upstream.
It is not safe to use LAR to filter when to go down the espfix path,
because the LDT is per-process (rather than per-thread) and another
thread might change the descriptors behind our back. Fortunately it
is always *safe* (if a bit slow) to go down the espfix path, and a
32-bit LDT stack segment is extremely rare.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from 3.2 commit 6806fa8b6795aba9be8742a8f598f60eed26f875)
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/x86/kernel/entry_32.S | 5 -----
1 file changed, 5 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 8b5370c..db7dbe7 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -571,11 +571,6 @@ ENTRY(iret_exc)
CFI_RESTORE_STATE
ldt_ss:
- larl PT_OLDSS(%esp), %eax
- jnz restore_nocheck
- testl $0x00400000, %eax # returning to 32bit stack?
- jnz restore_nocheck # allright, normal return
-
#ifdef CONFIG_PARAVIRT
/*
* The kernel can't run on a non-flat stack if paravirt mode
--
1.7.12.2.21.g234cd45.dirty
next prev parent reply other threads:[~2014-12-06 17:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-06 17:41 [ 01/25] net: sendmsg: fix failed backport of "fix NULL pointer dereference" Willy Tarreau
2014-12-06 17:41 ` [ 00/25] 2.6.32.65-longterm review Willy Tarreau
2014-12-08 0:58 ` Willy Tarreau
2014-12-06 17:41 ` [ 01/25] net: sendmsg: fix failed backport of "fix NULL pointer dereference" Willy Tarreau
2014-12-06 17:41 ` [ 02/25] x86, 64-bit: Move K8 B step iret fixup to fault entry asm Willy Tarreau
2014-12-06 17:41 ` [ 03/25] x86-64: Adjust frame type at paranoid_exit: Willy Tarreau
2014-12-06 17:41 ` [ 04/25] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels Willy Tarreau
2014-12-06 17:41 ` Willy Tarreau [this message]
2014-12-06 17:41 ` [ 06/25] x86-64, espfix: Dont leak bits 31:16 of %esp returning to 16-bit stack Willy Tarreau
2014-12-06 17:41 ` [ 07/25] x86, espfix: Move espfix definitions into a separate header file Willy Tarreau
2014-12-06 17:41 ` [ 08/25] x86, espfix: Fix broken header guard Willy Tarreau
2014-12-06 17:41 ` [ 09/25] x86, espfix: Make espfix64 a Kconfig option, fix UML Willy Tarreau
2014-12-06 17:41 ` [ 10/25] x86, espfix: Make it possible to disable 16-bit support Willy Tarreau
2014-12-08 2:58 ` Ben Hutchings
2014-12-08 7:11 ` Willy Tarreau
2014-12-06 17:41 ` [ 11/25] x86_64/entry/xen: Do not invoke espfix64 on Xen Willy Tarreau
2014-12-06 17:42 ` [ 12/25] x86/espfix/xen: Fix allocation of pages for paravirt page tables Willy Tarreau
2014-12-06 17:42 ` [ 13/25] x86_64, traps: Stop using IST for #SS Willy Tarreau
2014-12-06 17:42 ` [ 14/25] x86_64, traps: Fix the espfix64 #DF fixup and rewrite it in C Willy Tarreau
2014-12-06 17:42 ` [ 15/25] x86_64, traps: Rework bad_iret Willy Tarreau
2014-12-06 17:42 ` [ 16/25] net/l2tp: dont fall back on UDP [get|set]sockopt Willy Tarreau
2014-12-06 17:42 ` [ 17/25] ALSA: control: Dont access controls outside of protected regions Willy Tarreau
2014-12-06 17:42 ` [ 18/25] ALSA: control: Fix replacing user controls Willy Tarreau
2014-12-06 17:42 ` [ 19/25] USB: whiteheat: Added bounds checking for bulk command response Willy Tarreau
2014-12-06 17:42 ` [ 20/25] net: sctp: fix panic on duplicate ASCONF chunks Willy Tarreau
2014-12-06 17:42 ` [ 21/25] net: sctp: fix remote memory pressure from excessive queueing Willy Tarreau
2014-12-06 17:42 ` [ 22/25] udf: Avoid infinite loop when processing indirect ICBs Willy Tarreau
2014-12-06 17:42 ` [ 23/25] net: sctp: fix NULL pointer dereference in af->from_addr_param on malformed packet Willy Tarreau
2014-12-06 17:42 ` [ 24/25] mac80211: fix fragmentation code, particularly for encryption Willy Tarreau
2014-12-06 17:42 ` [ 25/25] ttusb-dec: buffer overflow in ioctl Willy Tarreau
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