Hello!
This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20240307 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan
You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:
Tue Mar 5 13:11:08 2024 +0000
f896d5e8726c ("usb: typec: ucsi: Register SOP/SOP' Discover Identity Responses")
Coverity reported the following:
*** CID 1584245: Null pointer dereferences (FORWARD_NULL)
drivers/usb/typec/ucsi/ucsi.c:1136 in ucsi_check_cable()
1130 }
1131
1132 ret = ucsi_register_cable(con);
1133 if (ret < 0)
1134 return ret;
1135
vvv CID 1584245: Null pointer dereferences (FORWARD_NULL)
vvv Passing "con" to "ucsi_get_cable_identity", which dereferences null "con->cable".
1136 ret = ucsi_get_cable_identity(con);
1137 if (ret < 0)
1138 return ret;
1139
1140 ret = ucsi_register_plug(con);
1141 if (ret < 0)
If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):
Reported-by: coverity-bot <[email protected]>
Addresses-Coverity-ID: 1584245 ("Null pointer dereferences")
Fixes: f896d5e8726c ("usb: typec: ucsi: Register SOP/SOP' Discover Identity Responses")
Thanks for your attention!
--
Coverity-bot
Hi,
On Thu, Mar 07, 2024 at 11:34:21AM -0800, coverity-bot wrote:
> Hello!
>
> This is an experimental semi-automated report about issues detected by
> Coverity from a scan of next-20240307 as part of the linux-next scan project:
> https://scan.coverity.com/projects/linux-next-weekly-scan
>
> You're getting this email because you were associated with the identified
> lines of code (noted below) that were touched by commits:
>
> Tue Mar 5 13:11:08 2024 +0000
> f896d5e8726c ("usb: typec: ucsi: Register SOP/SOP' Discover Identity Responses")
>
> Coverity reported the following:
>
> *** CID 1584245: Null pointer dereferences (FORWARD_NULL)
> drivers/usb/typec/ucsi/ucsi.c:1136 in ucsi_check_cable()
> 1130 }
> 1131
> 1132 ret = ucsi_register_cable(con);
> 1133 if (ret < 0)
> 1134 return ret;
> 1135
> vvv CID 1584245: Null pointer dereferences (FORWARD_NULL)
> vvv Passing "con" to "ucsi_get_cable_identity", which dereferences null "con->cable".
> 1136 ret = ucsi_get_cable_identity(con);
> 1137 if (ret < 0)
> 1138 return ret;
> 1139
> 1140 ret = ucsi_register_plug(con);
> 1141 if (ret < 0)
>
> If this is a false positive, please let us know so we can mark it as
> such, or teach the Coverity rules to be smarter. If not, please make
> sure fixes get into linux-next. :) For patches fixing this, please
> include these lines (but double-check the "Fixes" first):
This looks like a false positive to me. The code looks like this:
if (con->cable)
return 0;
[ ... ]
ret = ucsi_register_cable(con)
if (ret < 0)
return ret;
ret = ucsi_get_cable_identity(con);
[ ... ]
From the con->cable check coverity concludes that con->cable is
initially NULL. Later ucsi_register_cable() initializes con->cable
if successful. Coverity seems to miss this and still thinks that
con->cable is NULL. Then converity correctly notices that
ucsi_get_cable_identity() dereferences con->cable and complains.
regards Christian
On Thu, Mar 07, 2024 at 09:16:00PM +0100, Christian A. Ehrhardt wrote:
>
> Hi,
>
> On Thu, Mar 07, 2024 at 11:34:21AM -0800, coverity-bot wrote:
> > Hello!
> >
> > This is an experimental semi-automated report about issues detected by
> > Coverity from a scan of next-20240307 as part of the linux-next scan project:
> > https://scan.coverity.com/projects/linux-next-weekly-scan
> >
> > You're getting this email because you were associated with the identified
> > lines of code (noted below) that were touched by commits:
> >
> > Tue Mar 5 13:11:08 2024 +0000
> > f896d5e8726c ("usb: typec: ucsi: Register SOP/SOP' Discover Identity Responses")
> >
> > Coverity reported the following:
> >
> > *** CID 1584245: Null pointer dereferences (FORWARD_NULL)
> > drivers/usb/typec/ucsi/ucsi.c:1136 in ucsi_check_cable()
> > 1130 }
> > 1131
> > 1132 ret = ucsi_register_cable(con);
> > 1133 if (ret < 0)
> > 1134 return ret;
> > 1135
> > vvv CID 1584245: Null pointer dereferences (FORWARD_NULL)
> > vvv Passing "con" to "ucsi_get_cable_identity", which dereferences null "con->cable".
> > 1136 ret = ucsi_get_cable_identity(con);
> > 1137 if (ret < 0)
> > 1138 return ret;
> > 1139
> > 1140 ret = ucsi_register_plug(con);
> > 1141 if (ret < 0)
> >
> > If this is a false positive, please let us know so we can mark it as
> > such, or teach the Coverity rules to be smarter. If not, please make
> > sure fixes get into linux-next. :) For patches fixing this, please
> > include these lines (but double-check the "Fixes" first):
>
> This looks like a false positive to me. The code looks like this:
>
> if (con->cable)
> return 0;
> [ ... ]
> ret = ucsi_register_cable(con)
> if (ret < 0)
> return ret;
> ret = ucsi_get_cable_identity(con);
> [ ... ]
>
> From the con->cable check coverity concludes that con->cable is
> initially NULL. Later ucsi_register_cable() initializes con->cable
> if successful. Coverity seems to miss this and still thinks that
> con->cable is NULL. Then converity correctly notices that
> ucsi_get_cable_identity() dereferences con->cable and complains.
Ah-ha! Yes, the ucsi_register_cable() check seems to have been missed.
I think it's confused by:
cable = typec_register_cable(con->port, &desc);
if (IS_ERR(cable)) {
This isn't IS_ERR_OR_NULL, so it thinks cable might still be NULL, but
there's no path through typec_register_cable() where that can be true.
Thanks for taking a look!
-Kees
--
Kees Cook