From: Jiashuo Liang <liangjs@pku.edu.cn>
To: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, Jiashuo Liang <liangjs@pku.edu.cn>
Subject: [PATCH v2] x86/fault: Fix wrong signal when vsyscall fails with pkey
Date: Fri, 30 Jul 2021 11:01:52 +0800 [thread overview]
Message-ID: <20210730030152.249106-1-liangjs@pku.edu.cn> (raw)
The function __bad_area_nosemaphore() calls kernelmode_fixup_or_oops() with
parameter "signal" being "pkey", which will send a signal numbered "pkey".
This bug appears when the kernel fail to access user-given memory pages
that are protected by pkey, so it can go through 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, we will generate the wrong signal.
A new parameter "pkey" is added to kernelmode_fixup_or_oops() to fix it.
Fixes: 5042d40a264c ("x86/fault: Bypass no_context() for implicit kernel faults from usermode")
Signed-off-by: Jiashuo Liang <liangjs@pku.edu.cn>
---
Changes in v2:
- Use ARCH_DEFAULT_PKEY instead of 0 for unused pkey parameter.
arch/x86/mm/fault.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b2eefdefc108..84a2c8c4af73 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -710,7 +710,8 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code,
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 @@ void do_user_addr_fault(struct pt_regs *regs,
*/
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 @@ void do_user_addr_fault(struct pt_regs *regs,
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 @@ void do_user_addr_fault(struct pt_regs *regs,
/* 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;
}
--
2.32.0
next reply other threads:[~2021-07-30 3:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 3:01 Jiashuo Liang [this message]
2021-08-23 14:55 ` [PATCH v2] x86/fault: Fix wrong signal when vsyscall fails with pkey Dave Hansen
2021-09-19 4:39 ` Jiashuo Liang
2021-09-20 10:42 ` [tip: x86/urgent] " tip-bot2 for Jiashuo Liang
2021-09-20 14:43 ` Borislav Petkov
2021-09-20 20:37 ` tip-bot2 for Jiashuo Liang
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