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At the moment, UBSAN report will be serialized using a spin_lock(). On
RT-systems, spinlocks are turned to rt_spin_lock and may sleep. This
will result to the following splat if the undefined behavior is in a
context that can sleep:
BUG: sleeping function called from invalid context at /src/linux/kernel/locking/rtmutex.c:968
in_atomic(): 1, irqs_disabled(): 128, pid: 3447, name: make
1 lock held by make/3447:
#0: 000000009a966332 (&mm->mmap_sem){++++}, at: do_page_fault+0x140/0x4f8
irq event stamp: 6284
hardirqs last enabled at (6283): [<ffff000011326520>] _raw_spin_unlock_irqrestore+0x90/0xa0
hardirqs last disabled at (6284): [<ffff0000113262b0>] _raw_spin_lock_irqsave+0x30/0x78
softirqs last enabled at (2430): [<ffff000010088ef8>] fpsimd_restore_current_state+0x60/0xe8
softirqs last disabled at (2427): [<ffff000010088ec0>] fpsimd_restore_current_state+0x28/0xe8
Preemption disabled at:
[<ffff000011324a4c>] rt_mutex_futex_unlock+0x4c/0xb0
CPU: 3 PID: 3447 Comm: make Tainted: G W 5.2.14-rt7-01890-ge6e057589653 #911
Call trace:
dump_backtrace+0x0/0x148
show_stack+0x14/0x20
dump_stack+0xbc/0x104
___might_sleep+0x154/0x210
rt_spin_lock+0x68/0xa0
ubsan_prologue+0x30/0x68
handle_overflow+0x64/0xe0
__ubsan_handle_add_overflow+0x10/0x18
__lock_acquire+0x1c28/0x2a28
lock_acquire+0xf0/0x370
_raw_spin_lock_irqsave+0x58/0x78
rt_mutex_futex_unlock+0x4c/0xb0
rt_spin_unlock+0x28/0x70
get_page_from_freelist+0x428/0x2b60
__alloc_pages_nodemask+0x174/0x1708
alloc_pages_vma+0x1ac/0x238
__handle_mm_fault+0x4ac/0x10b0
handle_mm_fault+0x1d8/0x3b0
do_page_fault+0x1c8/0x4f8
do_translation_fault+0xb8/0xe0
do_mem_abort+0x3c/0x98
el0_da+0x20/0x24
The spin_lock() will protect against multiple CPUs to output a report
together, I guess to prevent them from being interleaved. However, they
can still interleave with other messages (and even splat from
__might_sleep).
So the lock usefulness seems pretty limited. Rather than trying to
accomodate RT-system by switching to a raw_spin_lock(), the lock is now
completely dropped.
Link: http://lkml.kernel.org/r/20190920100835.14999-1-julien.grall@arm.com
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reported-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
"The main changes in this cycle were:
- Cross-arch changes to move the linker sections for NOTES and
EXCEPTION_TABLE into the RO_DATA area, where they belong on most
architectures. (Kees Cook)
- Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to
trap jumps into the middle of those padding areas instead of
sliding execution. (Kees Cook)
- A thorough cleanup of symbol definitions within x86 assembler code.
The rather randomly named macros got streamlined around a
(hopefully) straightforward naming scheme:
SYM_START(name, linkage, align...)
SYM_END(name, sym_type)
SYM_FUNC_START(name)
SYM_FUNC_END(name)
SYM_CODE_START(name)
SYM_CODE_END(name)
SYM_DATA_START(name)
SYM_DATA_END(name)
etc - with about three times of these basic primitives with some
label, local symbol or attribute variant, expressed via postfixes.
No change in functionality intended. (Jiri Slaby)
- Misc other changes, cleanups and smaller fixes"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
x86/entry/64: Remove pointless jump in paranoid_exit
x86/entry/32: Remove unused resume_userspace label
x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o
m68k: Convert missed RODATA to RO_DATA
x86/vmlinux: Use INT3 instead of NOP for linker fill bytes
x86/mm: Report actual image regions in /proc/iomem
x86/mm: Report which part of kernel image is freed
x86/mm: Remove redundant address-of operators on addresses
xtensa: Move EXCEPTION_TABLE to RO_DATA segment
powerpc: Move EXCEPTION_TABLE to RO_DATA segment
parisc: Move EXCEPTION_TABLE to RO_DATA segment
microblaze: Move EXCEPTION_TABLE to RO_DATA segment
ia64: Move EXCEPTION_TABLE to RO_DATA segment
h8300: Move EXCEPTION_TABLE to RO_DATA segment
c6x: Move EXCEPTION_TABLE to RO_DATA segment
arm64: Move EXCEPTION_TABLE to RO_DATA segment
alpha: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment
x86/vmlinux: Actually use _etext for the end of the text segment
vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA
...
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In order to use 128-bit integer arithmetic in C code, the architecture
needs to have declared support for it by setting ARCH_SUPPORTS_INT128,
and it requires a version of the toolchain that supports this at build
time. This is why all existing tests for ARCH_SUPPORTS_INT128 also test
whether __SIZEOF_INT128__ is defined, since this is only the case for
compilers that can support 128-bit integers.
Let's fold this additional test into the Kconfig declaration of
ARCH_SUPPORTS_INT128 so that we can also use the symbol in Makefiles,
e.g., to decide whether a certain object needs to be included in the
first place.
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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uaccess regions
The new check_zeroed_user() function uses variable shifts inside of a
user_access_begin()/user_access_end() section and that results in GCC
emitting __ubsan_handle_shift_out_of_bounds() calls, even though
through value range analysis it would be able to see that the UB in
question is impossible.
Annotate and whitelist this UBSAN function; continued use of
user_access_begin()/user_access_end() will undoubtedly result in
further uses of function.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Cc: keescook@chromium.org
Cc: linux@rasmusvillemoes.dk
Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper")
Link: https://lkml.kernel.org/r/20191021131149.GA19358@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
"This is a series from Peter Zijlstra that adds x86 build-time uaccess
validation of SMAP to objtool, which will detect and warn about the
following uaccess API usage bugs and weirdnesses:
- call to %s() with UACCESS enabled
- return with UACCESS enabled
- return with UACCESS disabled from a UACCESS-safe function
- recursive UACCESS enable
- redundant UACCESS disable
- UACCESS-safe disables UACCESS
As it turns out not leaking uaccess permissions outside the intended
uaccess functionality is hard when the interfaces are complex and when
such bugs are mostly dormant.
As a bonus we now also check the DF flag. We had at least one
high-profile bug in that area in the early days of Linux, and the
checking is fairly simple. The checks performed and warnings emitted
are:
- call to %s() with DF set
- return with DF set
- return with modified stack frame
- recursive STD
- redundant CLD
It's all x86-only for now, but later on this can also be used for PAN
on ARM and objtool is fairly cross-platform in principle.
While all warnings emitted by this new checking facility that got
reported to us were fixed, there might be GCC version dependent
warnings that were not reported yet - which we'll address, should they
trigger.
The warnings are non-fatal build warnings"
* 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
sched/x86_64: Don't save flags on context switch
objtool: Add Direction Flag validation
objtool: Add UACCESS validation
objtool: Fix sibling call detection
objtool: Rewrite alt->skip_orig
objtool: Add --backtrace support
objtool: Rewrite add_ignores()
objtool: Handle function aliases
objtool: Set insn->func for alternatives
x86/uaccess, kcov: Disable stack protector
x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
x86/uaccess, ubsan: Fix UBSAN vs. SMAP
x86/uaccess, kasan: Fix KASAN vs SMAP
x86/smap: Ditch __stringify()
x86/uaccess: Introduce user_access_{save,restore}()
x86/uaccess, signal: Fix AC=1 bloat
x86/uaccess: Always inline user_access_begin()
x86/uaccess, xen: Suppress SMAP warnings
...
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The kernel the kernel is built with -Wvla for some time, so is not
supposed to have any variable length arrays. Remove vla bounds checking
from ubsan since it's useless now.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Building lib/ubsan.c with gcc-9 results in a ton of nasty warnings like
this one:
lib/ubsan.c warning: conflicting types for built-in function
‘__ubsan_handle_negate_overflow’; expected ‘void(void *, void *)’ [-Wbuiltin-declaration-mismatch]
The kernel's declarations of __ubsan_handle_*() often uses 'unsigned
long' types in parameters while GCC these parameters as 'void *' types,
hence the mismatch.
Fix this by using 'void *' to match GCC's declarations.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Fixes: c6d308534aef ("UBSAN: run-time undefined behavior sanity checker")
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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UBSAN can insert extra code in random locations; including AC=1
sections. Typically this code is not safe and needs wrapping.
So far, only __ubsan_handle_type_mismatch* have been observed in AC=1
sections and therefore only those are annotated.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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gcc-8 complains about the prototype for this function:
lib/ubsan.c:432:1: error: ignoring attribute 'noreturn' in declaration of a built-in function '__ubsan_handle_builtin_unreachable' because it conflicts with attribute 'const' [-Werror=attributes]
This is actually a GCC's bug. In GCC internals
__ubsan_handle_builtin_unreachable() declared with both 'noreturn' and
'const' attributes instead of only 'noreturn':
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84210
Workaround this by removing the noreturn attribute.
[aryabinin: add information about GCC bug in changelog]
Link: http://lkml.kernel.org/r/20181107144516.4587-1-aryabinin@virtuozzo.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Olof Johansson <olof@lixom.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Similarly to type mismatch checks, new GCC 8.x and Clang also changed for
ABI for returns_nonnull checks. While we can update our code to conform
the new ABI it's more reasonable to just remove it. Because it's just
dead code, we don't have any single user of returns_nonnull attribute in
the whole kernel.
And AFAIU the advantage that this attribute could bring would be mitigated
by -fno-delete-null-pointer-checks cflag that we use to build the kernel.
So it's unlikely we will have a lot of returns_nonnull attribute in
future.
So let's just remove the code, it has no use.
[aryabinin@virtuozzo.com: fix warning]
Link: http://lkml.kernel.org/r/20180122165711.11510-1-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/20180119152853.16806-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Sodagudi Prasad <psodagud@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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UBSAN=y fails to build with new GCC/clang:
arch/x86/kernel/head64.o: In function `sanitize_boot_params':
arch/x86/include/asm/bootparam_utils.h:37: undefined reference to `__ubsan_handle_type_mismatch_v1'
because Clang and GCC 8 slightly changed ABI for 'type mismatch' errors.
Compiler now uses new __ubsan_handle_type_mismatch_v1() function with
slightly modified 'struct type_mismatch_data'.
Let's add new 'struct type_mismatch_data_common' which is independent from
compiler's layout of 'struct type_mismatch_data'. And make
__ubsan_handle_type_mismatch[_v1]() functions transform compiler-dependent
type mismatch data to our internal representation. This way, we can
support both old and new compilers with minimal amount of change.
Link: http://lkml.kernel.org/r/20180119152853.16806-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Sodagudi Prasad <psodagud@codeaurora.org>
Cc: <stable@vger.kernel.org> [4.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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A vist from the spelling fairy.
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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handle_object_size_mismatch() used %pk to format a kernel pointer with
pr_err(). This seemed to be a misspelling for %pK, but using this to
format a kernel pointer does not make much sence here.
Therefore use %p instead, like in handle_missaligned_access().
Link: http://lkml.kernel.org/r/20160730083010.11569-1-nicolas.iooss_linux@m4x.org
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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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