[PATCH] powerpc: Make alignment exception always check exception table

STALE7296d

5 messages, 2 authors, 2006-11-01 · open the first message on its own page

[PATCH] powerpc: Make alignment exception always check exception table

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2006-11-01 03:11:07 

The alignment exception used to only check the exception table for
-EFAULT, not for other errors. That opens an oops window if we can
coerce the kernel into getting an alignment exception for other reasons
in what would normally be a user-protected accessor, which can be done
via some of the futex ops. This fixes it by always checking the
exception tables.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

This is 2.6.19 material and should probably go into stable as well.
(Greg: take it if paulus acks it and it applies :)

Index: linux-work/arch/powerpc/kernel/traps.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/traps.c	2006-10-23 14:41:37.000000000 +1000
+++ linux-work/arch/powerpc/kernel/traps.c	2006-10-30 13:59:41.000000000 +1100
@@ -843,7 +843,7 @@ void __kprobes program_check_exception(s
 
 void alignment_exception(struct pt_regs *regs)
 {
-	int fixed = 0;
+	int sig, fixed = 0;
 
 	/* we don't implement logging of alignment exceptions */
 	if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS))
@@ -856,15 +856,11 @@ void alignment_exception(struct pt_regs 
 	}
 
 	/* Operand address was bad */
-	if (fixed == -EFAULT) {
-		if (user_mode(regs))
-			_exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar);
-		else
-			/* Search exception table */
-			bad_page_fault(regs, regs->dar, SIGSEGV);
-		return;
-	}
-	_exception(SIGBUS, regs, BUS_ADRALN, regs->dar);
+	sig = fixed == -EFAULT ? SIGSEGV : SIGBUS;
+	if (user_mode(regs))
+		_exception(sig, regs, SEGV_ACCERR, regs->dar);
+	else
+		bad_page_fault(regs, regs->dar, sig);
 }
 
 void StackOverflow(struct pt_regs *regs)

[PATCH] powerpc: Make alignment exception always check exception table (#2)

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2006-11-01 03:43:54 

The alignment exception used to only check the exception table for
-EFAULT, not for other errors. That opens an oops window if we can
coerce the kernel into getting an alignment exception for other reasons
in what would normally be a user-protected accessor, which can be done
via some of the futex ops. This fixes it by always checking the
exception tables.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Paul: this version also fixes arch/ppc

This is 2.6.19 material and should probably go into stable as well.
(Greg: take it if paulus acks it and it applies :)

Index: linux-work/arch/powerpc/kernel/traps.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/traps.c	2006-10-23 14:41:37.000000000 +1000
+++ linux-work/arch/powerpc/kernel/traps.c	2006-10-30 13:59:41.000000000 +1100
@@ -843,7 +843,7 @@ void __kprobes program_check_exception(s
 
 void alignment_exception(struct pt_regs *regs)
 {
-	int fixed = 0;
+	int sig, fixed = 0;
 
 	/* we don't implement logging of alignment exceptions */
 	if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS))
@@ -856,15 +856,11 @@ void alignment_exception(struct pt_regs 
 	}
 
 	/* Operand address was bad */
-	if (fixed == -EFAULT) {
-		if (user_mode(regs))
-			_exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar);
-		else
-			/* Search exception table */
-			bad_page_fault(regs, regs->dar, SIGSEGV);
-		return;
-	}
-	_exception(SIGBUS, regs, BUS_ADRALN, regs->dar);
+	sig = fixed == -EFAULT ? SIGSEGV : SIGBUS;
+	if (user_mode(regs))
+		_exception(sig, regs, SEGV_ACCERR, regs->dar);
+	else
+		bad_page_fault(regs, regs->dar, sig);
 }
 
 void StackOverflow(struct pt_regs *regs)
Index: linux-work/arch/ppc/kernel/traps.c
===================================================================
--- linux-work.orig/arch/ppc/kernel/traps.c	2006-10-06 13:47:55.000000000 +1000
+++ linux-work/arch/ppc/kernel/traps.c	2006-11-01 14:39:44.000000000 +1100
@@ -708,7 +708,7 @@ void single_step_exception(struct pt_reg
 
 void alignment_exception(struct pt_regs *regs)
 {
-	int fixed;
+	int sig, fixed = 0;
 
 	fixed = fix_alignment(regs);
 	if (fixed == 1) {
@@ -716,15 +716,11 @@ void alignment_exception(struct pt_regs 
 		emulate_single_step(regs);
 		return;
 	}
-	if (fixed == -EFAULT) {
-		/* fixed == -EFAULT means the operand address was bad */
-		if (user_mode(regs))
-			_exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar);
-		else
-			bad_page_fault(regs, regs->dar, SIGSEGV);
-		return;
-	}
-	_exception(SIGBUS, regs, BUS_ADRALN, regs->dar);
+	sig = fixed == -EFAULT ? SIGSEGV : SIGBUS;
+	if (user_mode(regs))
+		_exception(sig, regs, SEGV_ACCERR, regs->dar);
+	else
+		bad_page_fault(regs, regs->dar, sig);
 }
 
 void StackOverflow(struct pt_regs *regs)

[PATCH] powerpc: Make alignment exception always check exception table (#3)

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2006-11-01 04:13:13 

The alignment exception used to only check the exception table for
-EFAULT, not for other errors. That opens an oops window if we can
coerce the kernel into getting an alignment exception for other reasons
in what would normally be a user-protected accessor, which can be done
via some of the futex ops. This fixes it by always checking the
exception tables.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Paul: this version sets the correct si_code

This is 2.6.19 material and should probably go into stable as well.
(Greg: take it if paulus acks it and it applies :)

Index: linux-work/arch/powerpc/kernel/traps.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/traps.c	2006-11-01 14:59:07.000000000 +1100
+++ linux-work/arch/powerpc/kernel/traps.c	2006-11-01 15:01:06.000000000 +1100
@@ -843,7 +843,7 @@ void __kprobes program_check_exception(s
 
 void alignment_exception(struct pt_regs *regs)
 {
-	int fixed = 0;
+	int sig, code, fixed = 0;
 
 	/* we don't implement logging of alignment exceptions */
 	if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS))
@@ -857,14 +857,16 @@ void alignment_exception(struct pt_regs 
 
 	/* Operand address was bad */
 	if (fixed == -EFAULT) {
-		if (user_mode(regs))
-			_exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar);
-		else
-			/* Search exception table */
-			bad_page_fault(regs, regs->dar, SIGSEGV);
-		return;
+		sig = SIGSEGV;
+		code = SEGV_ACCERR;
+	} else {
+		sig = SIGBUS;
+		code = BUS_ADRALN;
 	}
-	_exception(SIGBUS, regs, BUS_ADRALN, regs->dar);
+	if (user_mode(regs))
+		_exception(sig, regs, code, regs->dar);
+	else
+		bad_page_fault(regs, regs->dar, sig);
 }
 
 void StackOverflow(struct pt_regs *regs)
Index: linux-work/arch/ppc/kernel/traps.c
===================================================================
--- linux-work.orig/arch/ppc/kernel/traps.c	2006-11-01 14:59:07.000000000 +1100
+++ linux-work/arch/ppc/kernel/traps.c	2006-11-01 15:01:32.000000000 +1100
@@ -708,7 +708,7 @@ void single_step_exception(struct pt_reg
 
 void alignment_exception(struct pt_regs *regs)
 {
-	int fixed;
+	int sig, code, fixed = 0;
 
 	fixed = fix_alignment(regs);
 	if (fixed == 1) {
@@ -717,14 +717,16 @@ void alignment_exception(struct pt_regs 
 		return;
 	}
 	if (fixed == -EFAULT) {
-		/* fixed == -EFAULT means the operand address was bad */
-		if (user_mode(regs))
-			_exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar);
-		else
-			bad_page_fault(regs, regs->dar, SIGSEGV);
-		return;
+		sig = SIGSEGV;
+		code = SEGV_ACCERR;
+	} else {
+		sig = SIGBUS;
+		code = BUS_ADRALN;
 	}
-	_exception(SIGBUS, regs, BUS_ADRALN, regs->dar);
+	if (user_mode(regs))
+		_exception(sig, regs, code, regs->dar);
+	else
+		bad_page_fault(regs, regs->dar, sig);
 }
 
 void StackOverflow(struct pt_regs *regs)

Re: [PATCH] powerpc: Make alignment exception always check exception table

From: Greg KH <hidden>
Date: 2006-11-01 07:03:57 

On Wed, Nov 01, 2006 at 02:09:30PM +1100, Benjamin Herrenschmidt wrote:
The alignment exception used to only check the exception table for
-EFAULT, not for other errors. That opens an oops window if we can
coerce the kernel into getting an alignment exception for other reasons
in what would normally be a user-protected accessor, which can be done
via some of the futex ops. This fixes it by always checking the
exception tables.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

This is 2.6.19 material and should probably go into stable as well.
(Greg: take it if paulus acks it and it applies :)
Please forward the final patch (which ever version it is :) to the
stable@kernel.org address when this goes into mainline.

thanks,

greg k-h

Re: [PATCH] powerpc: Make alignment exception always check exception table

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2006-11-01 20:44:45 

On Tue, 2006-10-31 at 22:34 -0800, Greg KH wrote:
On Wed, Nov 01, 2006 at 02:09:30PM +1100, Benjamin Herrenschmidt wrote:
quoted
The alignment exception used to only check the exception table for
-EFAULT, not for other errors. That opens an oops window if we can
coerce the kernel into getting an alignment exception for other reasons
in what would normally be a user-protected accessor, which can be done
via some of the futex ops. This fixes it by always checking the
exception tables.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

This is 2.6.19 material and should probably go into stable as well.
(Greg: take it if paulus acks it and it applies :)
Please forward the final patch (which ever version it is :) to the
stable@kernel.org address when this goes into mainline.
Ok, will do. I wan't sure what the proper procedure was.

Cheers,
Ben.
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