Messages in this thread Patch in this message | | | Date | Wed, 15 Nov 2017 00:22:31 +0300 | From | Vitaly Lipatov <> | Subject | Re: [PATCH v3] fs/fcntl: restore checking against COMPAT_LOFF_T_MAX for F_GETLK64 |
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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
> >> 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.
-- С уважением, Виталий Липатов, Etersoft
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