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Date: Mon, 20 Sep 2021 20:37:01 -0000
From: "tip-bot2 for Jiashuo Liang" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: kernel test robot <lkp@...el.com>,
Jiashuo Liang <liangjs@....edu.cn>,
Borislav Petkov <bp@...e.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/fault: Fix wrong signal when vsyscall fails with pkey
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: d4ffd5df9d18031b6a53f934388726775b4452d3
Gitweb: https://git.kernel.org/tip/d4ffd5df9d18031b6a53f934388726775b4452d3
Author: Jiashuo Liang <liangjs@....edu.cn>
AuthorDate: Fri, 30 Jul 2021 11:01:52 +08:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Mon, 20 Sep 2021 22:28:47 +02:00
x86/fault: Fix wrong signal when vsyscall fails with pkey
The function __bad_area_nosemaphore() calls kernelmode_fixup_or_oops()
with the parameter @signal being actually @pkey, which will send a
signal numbered with the argument in @pkey.
This bug can be triggered when the kernel fails to access user-given
memory pages that are protected by a pkey, so it can go down the
do_user_addr_fault() path and pass the !user_mode() check in
__bad_area_nosemaphore().
Most cases will simply run the kernel fixup code to make an -EFAULT. But
when another condition current->thread.sig_on_uaccess_err is met, which
is only used to emulate vsyscall, the kernel will generate the wrong
signal.
Add a new parameter @pkey to kernelmode_fixup_or_oops() to fix this.
[ bp: Massage commit message, fix build error as reported by the 0day
bot: https://lkml.kernel.org/r/202109202245.APvuT8BX-lkp@intel.com ]
Fixes: 5042d40a264c ("x86/fault: Bypass no_context() for implicit kernel faults from usermode")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Jiashuo Liang <liangjs@....edu.cn>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lkml.kernel.org/r/20210730030152.249106-1-liangjs@pku.edu.cn
---
arch/x86/include/asm/pkeys.h | 2 --
arch/x86/mm/fault.c | 26 ++++++++++++++++++--------
include/linux/pkeys.h | 2 ++
3 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index 5c7bcaa..1d5f14a 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -2,8 +2,6 @@
#ifndef _ASM_X86_PKEYS_H
#define _ASM_X86_PKEYS_H
-#define ARCH_DEFAULT_PKEY 0
-
/*
* If more than 16 keys are ever supported, a thorough audit
* will be necessary to ensure that the types that store key
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b2eefde..84a2c8c 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -710,7 +710,8 @@ oops:
static noinline void
kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
- unsigned long address, int signal, int si_code)
+ unsigned long address, int signal, int si_code,
+ u32 pkey)
{
WARN_ON_ONCE(user_mode(regs));
@@ -735,8 +736,12 @@ kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
set_signal_archinfo(address, error_code);
- /* XXX: hwpoison faults will set the wrong code. */
- force_sig_fault(signal, si_code, (void __user *)address);
+ if (si_code == SEGV_PKUERR) {
+ force_sig_pkuerr((void __user *)address, pkey);
+ } else {
+ /* XXX: hwpoison faults will set the wrong code. */
+ force_sig_fault(signal, si_code, (void __user *)address);
+ }
}
/*
@@ -798,7 +803,8 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
struct task_struct *tsk = current;
if (!user_mode(regs)) {
- kernelmode_fixup_or_oops(regs, error_code, address, pkey, si_code);
+ kernelmode_fixup_or_oops(regs, error_code, address,
+ SIGSEGV, si_code, pkey);
return;
}
@@ -930,7 +936,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
{
/* Kernel mode? Handle exceptions or die: */
if (!user_mode(regs)) {
- kernelmode_fixup_or_oops(regs, error_code, address, SIGBUS, BUS_ADRERR);
+ kernelmode_fixup_or_oops(regs, error_code, address,
+ SIGBUS, BUS_ADRERR, ARCH_DEFAULT_PKEY);
return;
}
@@ -1396,7 +1403,8 @@ good_area:
*/
if (!user_mode(regs))
kernelmode_fixup_or_oops(regs, error_code, address,
- SIGBUS, BUS_ADRERR);
+ SIGBUS, BUS_ADRERR,
+ ARCH_DEFAULT_PKEY);
return;
}
@@ -1416,7 +1424,8 @@ good_area:
return;
if (fatal_signal_pending(current) && !user_mode(regs)) {
- kernelmode_fixup_or_oops(regs, error_code, address, 0, 0);
+ kernelmode_fixup_or_oops(regs, error_code, address,
+ 0, 0, ARCH_DEFAULT_PKEY);
return;
}
@@ -1424,7 +1433,8 @@ good_area:
/* Kernel mode? Handle exceptions or die: */
if (!user_mode(regs)) {
kernelmode_fixup_or_oops(regs, error_code, address,
- SIGSEGV, SEGV_MAPERR);
+ SIGSEGV, SEGV_MAPERR,
+ ARCH_DEFAULT_PKEY);
return;
}
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
index 6beb26b..86be8bf 100644
--- a/include/linux/pkeys.h
+++ b/include/linux/pkeys.h
@@ -4,6 +4,8 @@
#include <linux/mm.h>
+#define ARCH_DEFAULT_PKEY 0
+
#ifdef CONFIG_ARCH_HAS_PKEYS
#include <asm/pkeys.h>
#else /* ! CONFIG_ARCH_HAS_PKEYS */
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