On 10/03/2019 17.56, Konstantin Khlebnikov wrote: > Traditional scanf implementations ignore integer overflows because > C language standard allows here undefined behavior (ยง7.21.6.2 #10). > > So, sane and safe behavior wouldn't harm anything. > > This patch carefully checks integer overflows and stops matching if result > does not fit into appropriate type before assigning it into argument.
IIRC, this has been attempted before, causing a userspace regression because some sysfs/procfs file matched with %u or %x, and somebody wrote -1 to get 0xffffffff . I can't remember or find a reference right now, making the above a rather weak argument. However, please start the series with your test cases, before any refactoring. That makes it easier to see what behaviour you're changing (i.e., what used to be allowed is now treated as non-match, etc.). Rasmus
