On Mon 11-01-21 22:28:45, Andrew Morton wrote: > On Tue, 12 Jan 2021 14:24:05 +0800 Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote: > > > On 2021/1/12 12:33, Andrew Morton wrote: > > > On Tue, 12 Jan 2021 11:31:55 +0800 Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote: > > > > > >> The process_sysctl_arg() does not check whether val is empty before > > >> invoking strlen(val). If the command line parameter () is incorrectly > > >> configured and val is empty, oops is triggered. > > >> > > >> --- a/fs/proc/proc_sysctl.c > > >> +++ b/fs/proc/proc_sysctl.c > > >> @@ -1770,6 +1770,9 @@ static int process_sysctl_arg(char *param, char *val, > > >> return 0; > > >> } > > >> > > >> + if (!val) > > >> + return -EINVAL; > > >> + > > > > > > I think v2 (return 0) was preferable. Because all the other error-out > > > cases in process_sysctl_arg() also do a `return 0'. > > > > https://lore.kernel.org/lkml/bc098af4-c0cd-212e-d09d-46d617d0acab@xxxxxxxxxx/ > > > > patch4: > > +++ b/fs/proc/proc_sysctl.c > > @@ -1757,6 +1757,9 @@ static int process_sysctl_arg(char *param, > > char *val, > > loff_t pos = 0; > > ssize_t wret; > > > > + if (!val) > > + return 0; > > + > > if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) { > > param += sizeof("sysctl") - 1; > > > > Is this the version you're talking about? > > yes, but as a separate patch. The bugfix comes first. > > > > > > > If we're going to do a separate "patch: make process_sysctl_arg() > > > return an errno instead of 0" then fine, we can discuss that. But it's > > > conceptually a different work from fixing this situation. > > > . > > > > > However, are the logs generated by process_sysctl_arg() clearer and more > > accurate than parse_args()? Should the logs generated by > > process_sysctl_arg() be deleted? > > I think the individual logs are very useful and should be retained. Yes, other sysfs specific error messages are likely useful. I just fail to see why a missing value should be handled here when there is an existing handling in the caller. Not sure whether a complete shadow reporting in process_sysctl_arg is a deliberate decision or not. Vlastimil? Anyway one way or the other, all I care about is to have a reporting in place because this shouldn't be a silent failure. -- Michal Hocko SUSE Labs
