Commit 34173a4a authored by Miguel Ojeda's avatar Miguel Ojeda Committed by Linus Torvalds
Browse files

[PATCH] cfag12864b: fix crash when built-in and no parport present 



The problem comes when ks0108/cfag12864b are built-in and no parallel port is
present.  ks0108_init() is called first, as it should be, but fails to load
(as there is no parallel port to use).

After that, cfag12864b_init() gets called, without knowing anything about
ks0108 failed, and calls ks0108_writecontrol(), which dereferences an
uninitialized pointer.

Init order is OK, I think.  The problem is how to stop cfag12864b_init() being
called if ks0108 failed to load.  modprobe does it for us, but, how when
built-in?

Signed-off-by: default avatarMiguel Ojeda Sandonis <maxextreme@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e627432c

drivers/auxdisplay/cfag12864b.c

+19 −0
Original line number Diff line number Diff line
@@ -311,6 +311,17 @@ EXPORT_SYMBOL_GPL(cfag12864b_enable); 
EXPORT_SYMBOL_GPL(cfag12864b_disable);

EXPORT_SYMBOL_GPL(cfag12864b_isenabled);



/*

 * Is the module inited?

 */



static unsigned char cfag12864b_inited;

unsigned char cfag12864b_isinited(void)

{

	return cfag12864b_inited;

}

EXPORT_SYMBOL_GPL(cfag12864b_isinited);



/*

 * Module Init & Exit

 */
@@ -319,6 +330,13 @@ static int __init cfag12864b_init(void) 
{

	int ret = -EINVAL;



	/* ks0108_init() must be called first */

	if (!ks0108_isinited()) {

		printk(KERN_ERR CFAG12864B_NAME ": ERROR: "

			"ks0108 is not initialized\n");

		goto none;

	}



	if (PAGE_SIZE < CFAG12864B_SIZE) {

		printk(KERN_ERR CFAG12864B_NAME ": ERROR: "

			"page size (%i) < cfag12864b size (%i)\n",
@@ -354,6 +372,7 @@ static int __init cfag12864b_init(void) 
	cfag12864b_clear();

	cfag12864b_on();



	cfag12864b_inited = 1;

	return 0;



cachealloced:

drivers/auxdisplay/cfag12864bfb.c

+9 −1
Original line number Diff line number Diff line
@@ -137,7 +137,14 @@ static struct platform_device *cfag12864bfb_device; 


static int __init cfag12864bfb_init(void)

{

	int ret;

	int ret = -EINVAL;



	/* cfag12864b_init() must be called first */

	if (!cfag12864b_isinited()) {

		printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "

			"cfag12864b is not initialized\n");

		goto none;

	}



	if (cfag12864b_enable()) {

		printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
@@ -162,6 +169,7 @@ static int __init cfag12864bfb_init(void) 
		}

	}



none:

	return ret;

}

drivers/auxdisplay/ks0108.c

+12 −0
Original line number Diff line number Diff line
@@ -110,6 +110,17 @@ EXPORT_SYMBOL_GPL(ks0108_startline); 
EXPORT_SYMBOL_GPL(ks0108_address);

EXPORT_SYMBOL_GPL(ks0108_page);



/*

 * Is the module inited?

 */



static unsigned char ks0108_inited;

unsigned char ks0108_isinited(void)

{

	return ks0108_inited;

}

EXPORT_SYMBOL_GPL(ks0108_isinited);



/*

 * Module Init & Exit

 */
@@ -142,6 +153,7 @@ static int __init ks0108_init(void) 
		goto registered;

	}



	ks0108_inited = 1;

	return 0;



registered:

include/linux/cfag12864b.h

+5 −0
Original line number Diff line number Diff line
@@ -73,5 +73,10 @@ extern void cfag12864b_disable(void); 
 */

extern unsigned char cfag12864b_isenabled(void);



/*

 * Is the module inited?

 */

extern unsigned char cfag12864b_isinited(void);



#endif /* _CFAG12864B_H_ */

include/linux/ks0108.h

+3 −0
Original line number Diff line number Diff line
@@ -43,4 +43,7 @@ extern void ks0108_address(unsigned char address); 
/* Set the controller's current page (0..7) */

extern void ks0108_page(unsigned char page);



/* Is the module inited? */

extern unsigned char ks0108_isinited(void);



#endif /* _KS0108_H_ */

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