* [PATCH] i2c: i801: Don't generate an interrupt on bus reset
@ 2021-05-25 15:03 Jean Delvare
2021-05-26 9:10 ` Jarkko Nikula
2021-05-27 19:56 ` Wolfram Sang
0 siblings, 2 replies; 3+ messages in thread
From: Jean Delvare @ 2021-05-25 15:03 UTC (permalink / raw)
To: Linux I2C; +Cc: Andy Shevchenko, Jarkko Nikula, Heiner Kallweit
Now that the i2c-i801 driver supports interrupts, setting the KILL bit
in a attempt to recover from a timed out transaction triggers an
interrupt. Unfortunately, the interrupt handler (i801_isr) is not
prepared for this situation and will try to process the interrupt as
if it was signaling the end of a successful transaction. In the case
of a block transaction, this can result in an out-of-range memory
access.
This condition was reproduced several times by syzbot:
https://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e
https://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e
https://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e
https://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb
https://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a
https://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79
So disable interrupts while trying to reset the bus. Interrupts will
be enabled again for the following transaction.
Fixes: 636752bcb517 ("i2c-i801: Enable IRQ for SMBus transactions")
Reported-by: syzbot+b4d3fd1dfd53e90afd79@syzkaller.appspotmail.com
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
drivers/i2c/busses/i2c-i801.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- linux-5.12.orig/drivers/i2c/busses/i2c-i801.c 2021-05-24 12:00:59.307576983 +0200
+++ linux-5.12/drivers/i2c/busses/i2c-i801.c 2021-05-24 12:04:10.230998259 +0200
@@ -401,11 +401,9 @@ static int i801_check_post(struct i801_p
dev_err(&priv->pci_dev->dev, "Transaction timeout\n");
/* try to stop the current command */
dev_dbg(&priv->pci_dev->dev, "Terminating the current operation\n");
- outb_p(inb_p(SMBHSTCNT(priv)) | SMBHSTCNT_KILL,
- SMBHSTCNT(priv));
+ outb_p(SMBHSTCNT_KILL, SMBHSTCNT(priv));
usleep_range(1000, 2000);
- outb_p(inb_p(SMBHSTCNT(priv)) & (~SMBHSTCNT_KILL),
- SMBHSTCNT(priv));
+ outb_p(0, SMBHSTCNT(priv));
/* Check if it worked */
status = inb_p(SMBHSTSTS(priv));
--
Jean Delvare
SUSE L3 Support
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] i2c: i801: Don't generate an interrupt on bus reset
2021-05-25 15:03 [PATCH] i2c: i801: Don't generate an interrupt on bus reset Jean Delvare
@ 2021-05-26 9:10 ` Jarkko Nikula
2021-05-27 19:56 ` Wolfram Sang
1 sibling, 0 replies; 3+ messages in thread
From: Jarkko Nikula @ 2021-05-26 9:10 UTC (permalink / raw)
To: Jean Delvare, Linux I2C; +Cc: Andy Shevchenko, Heiner Kallweit
Hi
On 5/25/21 6:03 PM, Jean Delvare wrote:
> Now that the i2c-i801 driver supports interrupts, setting the KILL bit
> in a attempt to recover from a timed out transaction triggers an
> interrupt. Unfortunately, the interrupt handler (i801_isr) is not
> prepared for this situation and will try to process the interrupt as
> if it was signaling the end of a successful transaction. In the case
> of a block transaction, this can result in an out-of-range memory
> access.
>
> This condition was reproduced several times by syzbot:
> https://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e
> https://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e
> https://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e
> https://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb
> https://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a
> https://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79
>
> So disable interrupts while trying to reset the bus. Interrupts will
> be enabled again for the following transaction.
>
> Fixes: 636752bcb517 ("i2c-i801: Enable IRQ for SMBus transactions")
> Reported-by: syzbot+b4d3fd1dfd53e90afd79@syzkaller.appspotmail.com
> Signed-off-by: Jean Delvare <jdelvare@suse.de>
> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> ---
> drivers/i2c/busses/i2c-i801.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
I hope I managed to test this properly. At least I was able to trigger
KASAN quite easily and after your patch not anymore.
My test was to run "i2cdump -y 0 0x50 i" a few times with this hack:
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -653,6 +653,7 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
struct i801_priv *priv = dev_id;
u16 pcists;
u8 status;
+ static int count = 0;
/* Confirm this is our interrupt */
pci_read_config_word(priv->pci_dev, SMBPCISTS, &pcists);
@@ -676,8 +677,10 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS;
if (status) {
outb_p(status, SMBHSTSTS(priv));
- priv->status = status;
- wake_up(&priv->waitq);
+ if ((count++ % 10)) {
+ priv->status = status;
+ wake_up(&priv->waitq);
+ }
}
return IRQ_HANDLED;
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] i2c: i801: Don't generate an interrupt on bus reset
2021-05-25 15:03 [PATCH] i2c: i801: Don't generate an interrupt on bus reset Jean Delvare
2021-05-26 9:10 ` Jarkko Nikula
@ 2021-05-27 19:56 ` Wolfram Sang
1 sibling, 0 replies; 3+ messages in thread
From: Wolfram Sang @ 2021-05-27 19:56 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C, Andy Shevchenko, Jarkko Nikula, Heiner Kallweit
[-- Attachment #1: Type: text/plain, Size: 1421 bytes --]
On Tue, May 25, 2021 at 05:03:36PM +0200, Jean Delvare wrote:
> Now that the i2c-i801 driver supports interrupts, setting the KILL bit
> in a attempt to recover from a timed out transaction triggers an
> interrupt. Unfortunately, the interrupt handler (i801_isr) is not
> prepared for this situation and will try to process the interrupt as
> if it was signaling the end of a successful transaction. In the case
> of a block transaction, this can result in an out-of-range memory
> access.
>
> This condition was reproduced several times by syzbot:
> https://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e
> https://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e
> https://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e
> https://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb
> https://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a
> https://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79
>
> So disable interrupts while trying to reset the bus. Interrupts will
> be enabled again for the following transaction.
>
> Fixes: 636752bcb517 ("i2c-i801: Enable IRQ for SMBus transactions")
> Reported-by: syzbot+b4d3fd1dfd53e90afd79@syzkaller.appspotmail.com
> Signed-off-by: Jean Delvare <jdelvare@suse.de>
> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Applied to for-current, thanks!
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