2020-01-14 14:42:46

by Colin King

Subject: [PATCH][next] drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write

From: Colin Ian King <[email protected]>

The end of buffer check is off-by-one since the check is against
an index that is pre-incremented before a store to buf[]. Fix this
adjusting the bounds check appropriately.

Addresses-Coverity: ("Out-of-bounds write")
Fixes: 51bd6f291583 ("Add support for IPMB driver")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/char/ipmi/ipmb_dev_int.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
index 9fdae83e59e0..382b28f1cf2f 100644
--- a/drivers/char/ipmi/ipmb_dev_int.c
+++ b/drivers/char/ipmi/ipmb_dev_int.c
@@ -279,7 +279,7 @@ static int ipmb_slave_cb(struct i2c_client *client,
break;

case I2C_SLAVE_WRITE_RECEIVED:
- if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg))
+ if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg) - 1)
break;

buf[++ipmb_dev->msg_idx] = *val;
--
2.24.0

2020-01-14 15:51:27

by Asmaa Mnebhi

Subject: RE: [PATCH][next] drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write

Reviewed-by: Asmaa Mnebhi <[email protected]>

-----Original Message-----
From: Colin King <[email protected]>
Sent: Tuesday, January 14, 2020 9:41 AM
To: Corey Minyard <[email protected]>; Arnd Bergmann <[email protected]>; Greg Kroah-Hartman <[email protected]>; Vadim Pasternak <[email protected]>; Asmaa Mnebhi <[email protected]>; [email protected]
Cc: [email protected]; [email protected]
Subject: [PATCH][next] drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write

From: Colin Ian King <[email protected]>

The end of buffer check is off-by-one since the check is against an index that is pre-incremented before a store to buf[]. Fix this adjusting the bounds check appropriately.

Addresses-Coverity: ("Out-of-bounds write")
Fixes: 51bd6f291583 ("Add support for IPMB driver")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/char/ipmi/ipmb_dev_int.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
index 9fdae83e59e0..382b28f1cf2f 100644
--- a/drivers/char/ipmi/ipmb_dev_int.c
+++ b/drivers/char/ipmi/ipmb_dev_int.c
@@ -279,7 +279,7 @@ static int ipmb_slave_cb(struct i2c_client *client,
break;

case I2C_SLAVE_WRITE_RECEIVED:
- if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg))
+ if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg) - 1)
break;

buf[++ipmb_dev->msg_idx] = *val;
--
2.24.0

2020-01-20 17:04:30

by Corey Minyard

Subject: Re: [PATCH][next] drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write

On Tue, Jan 14, 2020 at 03:50:22PM +0000, Asmaa Mnebhi wrote:
> Reviewed-by: Asmaa Mnebhi <[email protected]>

Thanks, I've picked this up in my next tree.

-corey

>
> -----Original Message-----
> From: Colin King <[email protected]>
> Sent: Tuesday, January 14, 2020 9:41 AM
> To: Corey Minyard <[email protected]>; Arnd Bergmann <[email protected]>; Greg Kroah-Hartman <[email protected]>; Vadim Pasternak <[email protected]>; Asmaa Mnebhi <[email protected]>; [email protected]
> Cc: [email protected]; [email protected]
> Subject: [PATCH][next] drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write
>
> From: Colin Ian King <[email protected]>
>
> The end of buffer check is off-by-one since the check is against an index that is pre-incremented before a store to buf[]. Fix this adjusting the bounds check appropriately.
>
> Addresses-Coverity: ("Out-of-bounds write")
> Fixes: 51bd6f291583 ("Add support for IPMB driver")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/char/ipmi/ipmb_dev_int.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
> index 9fdae83e59e0..382b28f1cf2f 100644
> --- a/drivers/char/ipmi/ipmb_dev_int.c
> +++ b/drivers/char/ipmi/ipmb_dev_int.c
> @@ -279,7 +279,7 @@ static int ipmb_slave_cb(struct i2c_client *client,
> break;
>
> case I2C_SLAVE_WRITE_RECEIVED:
> - if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg))
> + if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg) - 1)
> break;
>
> buf[++ipmb_dev->msg_idx] = *val;
> --
> 2.24.0
>