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
