On 01.04.2015 00:45, Andrew Morton wrote: > On Sun, 29 Mar 2015 21:28:29 +0200 Heinrich Schuchardt <[email protected]> > wrote: > >> When converting unsigned long to int overflows may occur. >> These currently are not detected when writing to the sysctl >> file system. >> >> E.g. on a system where int has 32 bits and long has 64 bits >> echo 0x800001234 > /proc/sys/kernel/threads-max >> has the same effect as >> echo 0x1234 > /proc/sys/kernel/threads-max >> >> The patch adds the missing check in do_proc_dointvec_conv. >> >> With the patch an overflow will result in an error EINVAL when >> writing to the the sysctl file system. > > hm, why fix this? There's a small risk of breaking > accidentally-working userspace, but I expect we can live with that. > > But how big a problem is this, really? This behaviour is quite > expected, after all. >
The typical user of a Linux system has never read the Kernel code and possibly has limited programming experience. Furthermore in Documentation/sysctl/kernel.txt there is no hint that only 32-bit integers can be used. So why should this typical user expect that on a 64-bit system +3000000000 is considered a negative number? Now that we know this is a bug why shouldn't we fix it? Best regards Heinrich -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
