On Tue, Mar 16, 2010 at 03:22:33PM -0700, Roland Dreier wrote: > > > drivers/infiniband/core/user_mad.c +646 ib_umad_reg_agent() 'umm' 4 <= 6 > > 641 u32 *umm = (u32 *) ureq.method_mask; > > 642 int i; > > 643 > > 644 for (i = 0; i < BITS_TO_LONGS(IB_MGMT_MAX_METHODS); ++i) > > 645 req.method_mask[i] = > > 646 umm[i * 2] | ((u64) umm[i * 2 + 1] << 32); > > "umm" points to a array with 4 elements. > > i can be 0 to 3, so "i * 2" goes up to 6 > > And 4 <= 6 so it's a problem. > > Smatch also complained about "i * 2 + 1" but I didn't include that. > > It's a bit tricky, but I believe this is a false positive. The code in > question is compatibility handling for 32-bit userspace on a 64-bit > kernel. In that case the range of i will be 0 to 1 (IB_MGMT_MAX_METHODS > is 128, so BITS_TO_LONGS on that is 2), and so we will only access > elements 0, 1, 2, and 3 of umm[], which is OK. > > (Not sure how easily a static checker could find this; the code in > question is guarded by test of compat_method_mask, which can only be 1 > if ib_umad_reg_agent() is called from ib_umad_compat_ioctl(), which will > only be built with CONFIG_COMPAT set, which can only happen on a 64-bit > architecture -- but it seems a bit hard for a checker to follow all that) Smatch doesn't handle anything between functions yet. Once it does you could do something like: compat_method_mask = get_possible_range(this parameter); That would only be zero, because the other code is #ifdefed out. Then the rest is simple enough. It will take some months to get the inter-function stuff working though. regards, dan carpenter > -- > Roland Dreier <rolandd@xxxxxxxxx> > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/index.html -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
