This is a note to let you know that I've just added the patch titled
m68k: Disable/restore interrupts in hwreg_present()/hwreg_write()
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
m68k-disable-restore-interrupts-in-hwreg_present-hwreg_write.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e4dc601bf99ccd1c95b7e6eef1d3cf3c4b0d4961 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Date: Sun, 28 Sep 2014 10:50:06 +0200
Subject: m68k: Disable/restore interrupts in hwreg_present()/hwreg_write()
From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
commit e4dc601bf99ccd1c95b7e6eef1d3cf3c4b0d4961 upstream.
hwreg_present() and hwreg_write() temporarily change the VBR register to
another vector table. This table contains a valid bus error handler
only, all other entries point to arbitrary addresses.
If an interrupt comes in while the temporary table is active, the
processor will start executing at such an arbitrary address, and the
kernel will crash.
While most callers run early, before interrupts are enabled, or
explicitly disable interrupts, Finn Thain pointed out that macsonic has
one callsite that doesn't, causing intermittent boot crashes.
There's another unsafe callsite in hilkbd.
Fix this for good by disabling and restoring interrupts inside
hwreg_present() and hwreg_write().
Explicitly disabling interrupts can be removed from the callsites later.
Reported-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/m68k/mm/hwtest.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/arch/m68k/mm/hwtest.c
+++ b/arch/m68k/mm/hwtest.c
@@ -28,9 +28,11 @@
int hwreg_present( volatile void *regp )
{
int ret = 0;
+ unsigned long flags;
long save_sp, save_vbr;
long tmp_vectors[3];
+ local_irq_save(flags);
__asm__ __volatile__
( "movec %/vbr,%2\n\t"
"movel #Lberr1,%4@(8)\n\t"
@@ -46,6 +48,7 @@ int hwreg_present( volatile void *regp )
: "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr)
: "a" (regp), "a" (tmp_vectors)
);
+ local_irq_restore(flags);
return( ret );
}
@@ -58,9 +61,11 @@ EXPORT_SYMBOL(hwreg_present);
int hwreg_write( volatile void *regp, unsigned short val )
{
int ret;
+ unsigned long flags;
long save_sp, save_vbr;
long tmp_vectors[3];
+ local_irq_save(flags);
__asm__ __volatile__
( "movec %/vbr,%2\n\t"
"movel #Lberr2,%4@(8)\n\t"
@@ -78,6 +83,7 @@ int hwreg_write( volatile void *regp, un
: "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr)
: "a" (regp), "a" (tmp_vectors), "g" (val)
);
+ local_irq_restore(flags);
return( ret );
}
Patches currently in stable-queue which might be from geert@xxxxxxxxxxxxxx are
queue-3.17/m68k-disable-restore-interrupts-in-hwreg_present-hwreg_write.patch
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