On Wed, May 15, 2019 at 10:53:55PM +0800, Zhiqiang Liu wrote: > Friendly ping... > > 在 2019/4/24 12:04, Zhiqiang Liu 写道: > > > > Friendly ping... Hi! (Please include akpm on CC for next versions of this, as he's likely the person to take this patch.) > > > >> From: Zhiqiang Liu <liuzhiqiang26@xxxxxxxxxx> > >> > >> In proc_dointvec_jiffies func, the write value is only checked > >> whether it is larger than INT_MAX. If the write value is less > >> than zero, it can also be successfully writen in the data. This appears to be "be design", but I see many "unsigned int" users that might be tricked into giant values... (for example, see net/netfilter/nf_conntrack_standalone.c) Should proc_dointvec_jiffies() just be fixed to disallow negative values entirely? Looking at the implementation, it seems to be very intentional about accepting negative values. However, when I looked through a handful of proc_dointvec_jiffies() users, it looks like they're all expecting a positive value. Many in the networking subsystem are, in fact, writing to unsigned long variables, as I mentioned. Are there real-world cases of wanting to set a negative jiffie value via proc_dointvec_jiffies()? > >> > >> However, in some scenarios, users would adopt the data to > >> set timers or check whether time is expired. Generally, the data > >> will be cast to an unsigned type variable, then the negative data > >> becomes a very large unsigned value, which leads to long waits > >> or other unpredictable problems. > >> > >> Here, we add a new func, proc_dointvec_jiffies_minmax, to limit the > >> min/max write value, which is similar to the proc_dointvec_minmax func. > >> > >> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@xxxxxxxxxx> > >> Reported-by: Qiang Ning <ningqiang1@xxxxxxxxxx> > >> Reviewed-by: Jie Liu <liujie165@xxxxxxxxxx> If proc_dointvec_jiffies() can't just be fixed, where will the new function get used? It seems all the "unsigned int" users could benefit. -- Kees Cook
