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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jean Delvare <jdelvare@xxxxxxx>
Acked-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxxx>
