2021-10-05 15:17:30

by Colin King

[permalink] [raw]
Subject: [PATCH][next] ipmi: ipmb: Fix off-by-one size check on rcvlen

From: Colin Ian King <[email protected]>

There is an off-by-one bounds check on the rcvlen causing a potential
out of bounds write on iidev->rcvmsg. Fix this by using the >= operator
on the bounds check rather than the > operator.

Addresses-Coverity: ("Out-of-bounds write")
Fixes: 0ba0c3c5d1c1 ("ipmi:ipmb: Add initial support for IPMI over IPMB")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/char/ipmi/ipmi_ipmb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_ipmb.c b/drivers/char/ipmi/ipmi_ipmb.c
index b10a1fd9c563..77ebec4ed28e 100644
--- a/drivers/char/ipmi/ipmi_ipmb.c
+++ b/drivers/char/ipmi/ipmi_ipmb.c
@@ -192,7 +192,7 @@ static int ipmi_ipmb_slave_cb(struct i2c_client *client,
break;

case I2C_SLAVE_WRITE_RECEIVED:
- if (iidev->rcvlen > sizeof(iidev->rcvmsg))
+ if (iidev->rcvlen >= sizeof(iidev->rcvmsg))
iidev->overrun = true;
else
iidev->rcvmsg[iidev->rcvlen++] = *val;
--
2.32.0


2021-10-05 15:41:38

by Corey Minyard

[permalink] [raw]
Subject: Re: [Openipmi-developer] [PATCH][next] ipmi: ipmb: Fix off-by-one size check on rcvlen

On Tue, Oct 05, 2021 at 04:16:11PM +0100, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> There is an off-by-one bounds check on the rcvlen causing a potential
> out of bounds write on iidev->rcvmsg. Fix this by using the >= operator
> on the bounds check rather than the > operator.

Got it, thanks.

-corey

>
> Addresses-Coverity: ("Out-of-bounds write")
> Fixes: 0ba0c3c5d1c1 ("ipmi:ipmb: Add initial support for IPMI over IPMB")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/char/ipmi/ipmi_ipmb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ipmb.c b/drivers/char/ipmi/ipmi_ipmb.c
> index b10a1fd9c563..77ebec4ed28e 100644
> --- a/drivers/char/ipmi/ipmi_ipmb.c
> +++ b/drivers/char/ipmi/ipmi_ipmb.c
> @@ -192,7 +192,7 @@ static int ipmi_ipmb_slave_cb(struct i2c_client *client,
> break;
>
> case I2C_SLAVE_WRITE_RECEIVED:
> - if (iidev->rcvlen > sizeof(iidev->rcvmsg))
> + if (iidev->rcvlen >= sizeof(iidev->rcvmsg))
> iidev->overrun = true;
> else
> iidev->rcvmsg[iidev->rcvlen++] = *val;
> --
> 2.32.0
>
>
>
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