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Date: Mon, 8 May 2017 09:52:09 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Thomas Garnier <thgarnie@...gle.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Dave Hansen <dave.hansen@...el.com>, Arnd Bergmann <arnd@...db.de>,
Thomas Gleixner <tglx@...utronix.de>,
David Howells <dhowells@...hat.com>,
René Nyffenegger <mail@...enyffenegger.ch>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
Oleg Nesterov <oleg@...hat.com>,
Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>, Rik van Riel <riel@...hat.com>,
Kees Cook <keescook@...omium.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Borislav Petkov <bp@...en8.de>, Brian Gerst <brgerst@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Russell King <linux@...linux.org.uk>,
Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>,
Mark Rutland <mark.rutland@....com>,
James Morse <james.morse@....com>,
linux-s390 <linux-s390@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
the arch/x86 maintainers <x86@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH v9 1/4] syscalls: Verify address limit before returning
to user-mode
* Ingo Molnar <mingo@...nel.org> wrote:
> ... and even a relatively simple static analysis tool ought to be able to see
> through that.
>
> I'd even suggest we do it not like Sparse builds are done today, but in a more
> integrated fashion: do static analysis as part of a typical kernel defconfig
> build and not tolerate warnings but go for a 'zero warnings' policy like Linus
> uses for modconfig builds.
>
> _That_ solution I'd feel very, very good about - it would be so much better than
> any runtime checks...
So the problem I have with Sparse is that it is very spammy. For example:
make C=1 kernel/sched/
... produces:
kernel/sched/core.c:792:6: warning: symbol 'sched_set_stop_task' was not declared. Should it be static?
kernel/sched/core.c:1298:5: warning: symbol 'migrate_swap' was not declared. Should it be static?
kernel/sched/core.c:3648:35: warning: symbol 'preempt_schedule_irq' was not declared. Should it be static?
./include/linux/uaccess.h:166:18: warning: incorrect type in argument 1 (different modifiers)
./include/linux/uaccess.h:166:18: expected void *<noident>
./include/linux/uaccess.h:166:18: got void const *from
./include/linux/uaccess.h:166:18: warning: incorrect type in argument 1 (different modifiers)
./include/linux/uaccess.h:166:18: expected void *<noident>
./include/linux/uaccess.h:166:18: got void const *from
./include/linux/uaccess.h:166:18: warning: incorrect type in argument 1 (different modifiers)
./include/linux/uaccess.h:166:18: expected void *<noident>
./include/linux/uaccess.h:166:18: got void const *from
./include/linux/uaccess.h:166:18: warning: incorrect type in argument 1 (different modifiers)
./include/linux/uaccess.h:166:18: expected void *<noident>
./include/linux/uaccess.h:166:18: got void const *from
kernel/sched/clock.c:80:19: warning: symbol 'sched_clock_running' was not declared. Should it be static?
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
kernel/sched/cputime.c:335:33: warning: context imbalance in 'thread_group_cputime' - different lock contexts for basic block
kernel/sched/fair.c:54:14: warning: symbol 'normalized_sysctl_sched_latency' was not declared. Should it be static?
kernel/sched/fair.c:75:14: warning: symbol 'normalized_sysctl_sched_min_granularity' was not declared. Should it be static?
kernel/sched/fair.c:98:14: warning: symbol 'normalized_sysctl_sched_wakeup_granularity' was not declared. Should it be static?
kernel/sched/fair.c:132:14: warning: symbol 'capacity_margin' was not declared. Should it be static?
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/fair.c:4688:35: error: marked inline, but without a definition
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/fair.c:5817:19: error: cannot dereference this type
kernel/sched/fair.c:5817:19: error: cannot dereference this type
kernel/sched/fair.c:5817:19: error: internal error: bad type in derived(11)
kernel/sched/fair.c:5817:19: error: cannot dereference this type
kernel/sched/fair.c:5817:19: error: incompatible types in comparison expression (different base types)
kernel/sched/fair.c:5817:19: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/rt.c:635:6: warning: symbol 'sched_rt_bandwidth_account' was not declared. Should it be static?
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: internal error: bad type in derived(11)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
kernel/sched/sched.h:1988:16: error: incompatible types in comparison expression (different base types)
kernel/sched/sched.h:1988:16: error: cannot dereference this type
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
./include/linux/sched/cputime.h:83:14: warning: expression using sizeof bool
kernel/sched/topology.c:499:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:499:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:499:28: got struct sched_domain **<noident>
kernel/sched/topology.c:534:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:534:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:534:28: got struct sched_domain **<noident>
kernel/sched/topology.c:554:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:554:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:554:28: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:594:36: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:594:36: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:594:36: got struct sched_domain **<noident>
kernel/sched/topology.c:601:24: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:601:24: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:601:24: got struct sched_group **<noident>
kernel/sched/topology.c:602:31: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:602:31: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:602:31: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:1330:39: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1330:39: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1330:39: got struct sched_domain **<noident>
kernel/sched/topology.c:1333:40: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1333:40: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1333:40: got struct sched_domain **<noident>
kernel/sched/topology.c:1337:40: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1337:40: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1337:40: got struct sched_domain_shared **<noident>
kernel/sched/topology.c:1339:40: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1339:40: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1339:40: got struct sched_group **<noident>
kernel/sched/topology.c:1341:40: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1341:40: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1341:40: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:1343:32: warning: incorrect type in argument 1 (different address spaces)
kernel/sched/topology.c:1343:32: expected void [noderef] <asn:3>*__pdata
kernel/sched/topology.c:1343:32: got struct sched_domain **[noderef] sd
kernel/sched/topology.c:1345:32: warning: incorrect type in argument 1 (different address spaces)
kernel/sched/topology.c:1345:32: expected void [noderef] <asn:3>*__pdata
kernel/sched/topology.c:1345:32: got struct sched_domain_shared **[noderef] sds
kernel/sched/topology.c:1347:32: warning: incorrect type in argument 1 (different address spaces)
kernel/sched/topology.c:1347:32: expected void [noderef] <asn:3>*__pdata
kernel/sched/topology.c:1347:32: got struct sched_group **[noderef] sg
kernel/sched/topology.c:1349:32: warning: incorrect type in argument 1 (different address spaces)
kernel/sched/topology.c:1349:32: expected void [noderef] <asn:3>*__pdata
kernel/sched/topology.c:1349:32: got struct sched_group_capacity **[noderef] sgc
kernel/sched/topology.c:1261:25: warning: incorrect type in assignment (different address spaces)
kernel/sched/topology.c:1261:25: expected struct sched_domain **[noderef] sd
kernel/sched/topology.c:1261:25: got struct sched_domain *[noderef] <asn:3>*<noident>
kernel/sched/topology.c:1265:26: warning: incorrect type in assignment (different address spaces)
kernel/sched/topology.c:1265:26: expected struct sched_domain_shared **[noderef] sds
kernel/sched/topology.c:1265:26: got struct sched_domain_shared *[noderef] <asn:3>*<noident>
kernel/sched/topology.c:1269:25: warning: incorrect type in assignment (different address spaces)
kernel/sched/topology.c:1269:25: expected struct sched_group **[noderef] sg
kernel/sched/topology.c:1269:25: got struct sched_group *[noderef] <asn:3>*<noident>
kernel/sched/topology.c:1273:26: warning: incorrect type in assignment (different address spaces)
kernel/sched/topology.c:1273:26: expected struct sched_group_capacity **[noderef] sgc
kernel/sched/topology.c:1273:26: got struct sched_group_capacity *[noderef] <asn:3>*<noident>
kernel/sched/topology.c:1288:26: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1288:26: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1288:26: got struct sched_domain **<noident>
kernel/sched/topology.c:1295:26: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1295:26: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1295:26: got struct sched_domain_shared **<noident>
kernel/sched/topology.c:1304:26: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1304:26: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1304:26: got struct sched_group **<noident>
kernel/sched/topology.c:1311:26: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1311:26: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1311:26: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:759:30: warning: incorrect type in argument 1 (different address spaces)
kernel/sched/topology.c:759:30: expected void [noderef] <asn:3>*__pdata
kernel/sched/topology.c:759:30: got struct sched_domain **[noderef] sd
kernel/sched/topology.c:776:15: warning: incorrect type in assignment (different address spaces)
kernel/sched/topology.c:776:15: expected struct sched_domain **[noderef] sd
kernel/sched/topology.c:776:15: got struct sched_domain *[noderef] <asn:3>*<noident>
kernel/sched/topology.c:794:9: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:794:9: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:794:9: got struct sched_domain **<noident>
kernel/sched/topology.c:795:10: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:795:10: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:795:10: got struct sched_domain **<noident>
kernel/sched/topology.c:797:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:797:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:797:28: got struct sched_domain_shared **<noident>
kernel/sched/topology.c:798:18: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:798:18: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:798:18: got struct sched_domain_shared **<noident>
kernel/sched/topology.c:800:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:800:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:800:28: got struct sched_group **<noident>
kernel/sched/topology.c:801:18: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:801:18: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:801:18: got struct sched_group **<noident>
kernel/sched/topology.c:803:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:803:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:803:28: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:804:18: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:804:18: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:804:18: got struct sched_group_capacity **<noident>
kernel/sched/topology.c:848:36: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:848:36: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:848:36: got struct sched_domain **<noident>
kernel/sched/topology.c:954:31: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:954:31: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:954:31: got struct sched_domain_shared **<noident>
kernel/sched/topology.c:1354:21: warning: symbol 'build_sched_domain' was not declared. Should it be static?
kernel/sched/topology.c:1409:34: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1409:34: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1409:34: got struct sched_domain **<noident>
kernel/sched/topology.c:1419:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1419:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1419:28: got struct sched_domain **<noident>
kernel/sched/topology.c:1436:28: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1436:28: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1436:28: got struct sched_domain **<noident>
kernel/sched/topology.c:1446:23: warning: incorrect type in initializer (different address spaces)
kernel/sched/topology.c:1446:23: expected void const [noderef] <asn:3>*__vpp_verify
kernel/sched/topology.c:1446:23: got struct sched_domain **<noident>
kernel/sched/topology.c:759:29: warning: dereference of noderef expression
kernel/sched/topology.c:777:14: warning: dereference of noderef expression
kernel/sched/topology.c:1262:22: warning: dereference of noderef expression
kernel/sched/topology.c:1266:22: warning: dereference of noderef expression
kernel/sched/topology.c:1270:22: warning: dereference of noderef expression
kernel/sched/topology.c:1274:22: warning: dereference of noderef expression
kernel/sched/topology.c:1329:29: warning: dereference of noderef expression
kernel/sched/topology.c:1336:29: warning: dereference of noderef expression
kernel/sched/topology.c:1338:29: warning: dereference of noderef expression
kernel/sched/topology.c:1340:29: warning: dereference of noderef expression
kernel/sched/topology.c:1343:29: warning: dereference of noderef expression
kernel/sched/topology.c:1344:17: warning: dereference of noderef expression
kernel/sched/topology.c:1345:29: warning: dereference of noderef expression
kernel/sched/topology.c:1346:17: warning: dereference of noderef expression
kernel/sched/topology.c:1347:29: warning: dereference of noderef expression
kernel/sched/topology.c:1348:17: warning: dereference of noderef expression
kernel/sched/topology.c:1349:29: warning: dereference of noderef expression
kernel/sched/topology.c:1350:17: warning: dereference of noderef expression
... it's just not usable in that form for a regular maintenance flow.
So what would be more useful is to add a specific Sparse check that only checks
KERNEL_DS, to add it as a regular (.config driven) build option and make sure the
kernel build has zero warnings.
>From that point on we can declare that this kind of bug won't occur anymore, if
the Sparse implementation of the check is correct.
But there's a (big) problem with that development model: Sparse is not part of the
kernel tree and adding a feature to it while making the kernel depend on that
brand new feature is a logistical nightmare. The overhead is quite similar to
adding new features to a compiler - it happens at a glacial pace and is only done
for major features really, at considerable expense. I don't think this is an
adequate model for 'extended syntax checking' of the kernel, especially when it
comes to correctness that has such obvious security impact.
Thanks,
Ingo
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