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* lib/ubsan: remove null-pointer checksAndrey Ryabinin2018-08-101-11/+0
| | | | | | | | | | | | | | | | | | | With gcc-8 fsanitize=null become very noisy. GCC started to complain about things like &a->b, where 'a' is NULL pointer. There is no NULL dereference, we just calculate address to struct member. It's technically undefined behavior so UBSAN is correct to report it. But as long as there is no real NULL-dereference, I think, we should be fine. -fno-delete-null-pointer-checks compiler flag should protect us from any consequences. So let's just no use -fsanitize=null as it's not useful for us. If there is a real NULL-deref we will see crash. Even if userspace mapped something at NULL (root can do this), with things like SMAP should catch the issue. Link: http://lkml.kernel.org/r/20180802153209.813-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: add testing module for UBSANJinbum Park2018-04-111-0/+7
| | | | | | | | | | | | | | | | | | This is a test module for UBSAN. It triggers all undefined behaviors that linux supports now, and detect them. All test-cases have passed by compiling with gcc-5.5.0. If use gcc-4.9.x, misaligned, out-of-bounds, object-size-mismatch will not be detected. Because gcc-4.9.x doesn't support them. Link: http://lkml.kernel.org/r/20180309102247.GA2944@pjb1027-Latitude-E5410 Signed-off-by: Jinbum Park <jinb.park7@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Kconfig: lib/Kconfig.ubsan fix reference to ubsan documentationAndreas Platschek2016-12-141-1/+2
| | | | | | | | | | Documenation/ubsan.txt was moved to Documentation/dev-tools/ubsan.rst, this fixes the reference. Link: http://lkml.kernel.org/r/1476698152-29340-3-git-send-email-andreas.platschek@opentech.at Signed-off-by: Andreas Platschek <andreas.platschek@opentech.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ubsan: allow to disable the null sanitizerChristian Borntraeger2016-09-201-0/+11
| | | | | | | | | | | Some architectures use a hardware defined structure at address zero. Checking for a null pointer will result in many ubsan reports. Allow users to disable the null sanitizer. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* ubsan: fix tree-wide -Wmaybe-uninitialized false positivesAndrey Ryabinin2016-03-221-0/+5
| | | | | | | | | | | | | | | | | -fsanitize=* options makes GCC less smart than usual and increase number of 'maybe-uninitialized' false-positives. So this patch does two things: * Add -Wno-maybe-uninitialized to CFLAGS_UBSAN which will disable all such warnings for instrumented files. * Remove CONFIG_UBSAN_SANITIZE_ALL from all[yes|mod]config builds. So the all[yes|mod]config build goes without -fsanitize=* and still with -Wmaybe-uninitialized. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ubsan: cosmetic fix to Kconfig textYang Shi2016-02-111-1/+3
| | | | | | | | | | | | When enabling UBSAN_SANITIZE_ALL, the kernel image size gets increased significantly (~3x). So, it sounds better to have some note in Kconfig. And, fixed a typo. Signed-off-by: Yang Shi <yang.shi@linaro.org> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* UBSAN: run-time undefined behavior sanity checkerAndrey Ryabinin2016-01-201-0/+29
UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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