On Wed, 2017-11-15 at 00:22 +0300, Vitaly Lipatov wrote: > Jeff Layton писал 14.11.17 23:19: > > On Tue, 2017-11-14 at 22:25 +0300, Vitaly Lipatov wrote: > > > Jeff Layton писал 14.11.17 22:12: > > > ... > > > > Wait... > > > > > > > > Does this do anything at all in the case where you pass in > > > > COMPAT_LOFF_T_MAX? l_start and l_len are either off_t or loff_t > > > > (depending on arch). > > > > > > > > Either one will fit in the F_GETLK64/F_OFD_GETLK struct, so I don't see > > > > a need to check here. > > > > > > I am not sure, can off_t be bigger than loff_t ? > > > > I don't think so, at least not in any possible situation we care about > > here. > > We have this checking for ages: > if (f.l_start > COMPAT_LOFF_T_MAX) > ret = -EOVERFLOW; > http://debian.securedservers.com/kernel/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15-rc5-mm1/broken-out/fix-overflow-tests-for-compat_sys_fcntl64-locking.patch > I'm not convinced that those checks ever did anything, tbh. > > > > > If not, we have just skip checking against COMPAT_LOFF_T_MAX. > > > > > > ... > > > > > @@ -644,7 +644,7 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, > > > > > unsigned int, cmd, > > > > > err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); > > > > > if (err) > > > > > break; > > > > > - err = fixup_compat_flock(&flock); > > > > > + err = fixup_compat_flock(&flock, COMPAT_LOFF_T_MAX); > > > > > if (err) > > > > > return err; > > > > > err = put_compat_flock64(&flock, compat_ptr(arg)); > > > > > > > > Maybe a simpler fix would be to just remove the fixup_compat_flock call > > > > above? > > > > > > > > Ok. If you have a test for this, mind testing and sending a patch? > > I think if COMPAT_LOFF_T_MAX is exists, that value can be smaller than > can fit in off_t. > Checking against COMPAT_LOFF_T_MAX keep old logic works for me last 10 > years. > > I have some tests around wine project I worked on. May be later I will > do additional tests. > I am making an assumption here that l_start and l_end can never be larger than a signed 64-bit value. I don't see how it ever could be, given that it's defined as a long long, but I suppose we could add some exotic arch later that does something weird. Maybe we can just add a BUILD_BUG_ON for that? I'll send along an alternate patch in a few mins. -- Jeff Layton <jlayton@xxxxxxxxxx>
