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* [PATCH] x86/fault: Fix wrong signal when vsyscall fails with pkey
@ 2021-07-28 11:44 Jiashuo Liang
  2021-07-28 17:57 ` Dave Hansen
  0 siblings, 1 reply; 5+ messages in thread
From: Jiashuo Liang @ 2021-07-28 11:44 UTC (permalink / raw)
  To: Dave Hansen, Andy Lutomirski, Peter Zijlstra, Thomas Gleixner,
	Ingo Molnar, Borislav Petkov, x86, H. Peter Anvin
  Cc: linux-kernel, Jiashuo Liang

The function __bad_area_nosemaphore calls kernelmode_fixup_or_oops with
parameter "signal" being "pkey", which will send a signal numbered "pkey".

When emulating vsyscall, the kernel may fail to access user-given memory
pages that are protected by pkey. In such a case, the kernel should send a
SIGSEGV signal with si_code=SEGV_PKUERR and si_pkey=pkey.

So a new parameter "pkey" is added to kernelmode_fixup_or_oops to fix it.

Signed-off-by: Jiashuo Liang <liangjs@pku.edu.cn>
---
 arch/x86/mm/fault.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b2eefdefc108..883294282e1e 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, 0);
 		return;
 	}
 
@@ -1396,7 +1403,7 @@ 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, 0);
 		return;
 	}
 
@@ -1416,7 +1423,7 @@ 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, 0);
 		return;
 	}
 
@@ -1424,7 +1431,7 @@ 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, 0);
 			return;
 		}
 
-- 
2.32.0


^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-08-11  0:59 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-28 11:44 [PATCH] x86/fault: Fix wrong signal when vsyscall fails with pkey Jiashuo Liang
2021-07-28 17:57 ` Dave Hansen
2021-07-29  6:24   ` Jiashuo Liang
2021-07-29 14:02     ` Dave Hansen
2021-08-11  0:58       ` Jiashuo Liang

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