On Thu, Aug 17, 2017 at 12:50:37PM +0300, Dan Carpenter wrote: > On Thu, Aug 17, 2017 at 12:37:00PM +0300, Imre Deak wrote: > > On Thu, Aug 17, 2017 at 09:23:10AM +0300, Dan Carpenter wrote: > > > There are some potential integer overflows here on 64 bit systems. > > > > > > The condition "if (nfences > SIZE_MAX / sizeof(*fences))" can only be > > > true on 32 bit systems, it's a no-op on 64 bit, so let's ignore the > > > check for now and look a couple lines after: > > > > > > if (!access_ok(VERIFY_READ, user, nfences * 2 * sizeof(u32))) > > > ^^^^^^^^^^^ > > > "nfences" is an unsigned int, so if we set it to UINT_MAX and multiply > > > by two, it's going to have an integer overflow. > > > > AFAICS it wouldn't overflow due the promotion to unsigned long > > by '* sizeof(u32)'. > > > > It first multplies "nfences * 2" as unsigned int, then it type promotes > to size_t and multiplies by sizeof(). Only the first multiplication has > an integer overflow bug. Err, that's correct. Sorry for the noise. > > regards, > dan carpenter > _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
