2e08ca18 - kfence: avoid passing -g for test

Thu, 16 Mar 2023 22:47:04 +0000

kfence: avoid passing -g for testNathan reported that when building with GNU as and a version of clang thatdefaults to DWARF5: $ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- \ LLVM=1 LLVM_IAS=0 O=build \ mrproper allmodconfig mm/kfence/kfence_test.o /tmp/kfence_test-08a0a0.s: Assembler messages: /tmp/kfence_test-08a0a0.s:14627: Error: non-constant .uleb128 is not supported /tmp/kfence_test-08a0a0.s:14628: Error: non-constant .uleb128 is not supported /tmp/kfence_test-08a0a0.s:14632: Error: non-constant .uleb128 is not supported /tmp/kfence_test-08a0a0.s:14633: Error: non-constant .uleb128 is not supported /tmp/kfence_test-08a0a0.s:14639: Error: non-constant .uleb128 is not supported ...This is because `-g` defaults to the compiler debug info default. If theassembler does not support some of the directives used, the above errorsoccur. To fix, remove the explicit passing of `-g`.All the test wants is that stack traces print valid function names, anddebug info is not required for that. (I currently cannot recall why Iadded the explicit `-g`.)Link: https://lkml.kernel.org/r/20230316224705.709984-1-elver@google.comFixes: bc8fbc5f305a ("kfence: add test suite")Signed-off-by: Marco Elver Reported-by: Nathan Chancellor Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Signed-off-by: Andrew Morton List of files: /linux-6.15/mm/kfence/Makefile

56eb8e94 - mm/kfence: remove unnecessary CONFIG_KFENCE option

Tue, 22 Mar 2022 21:48:07 +0000

mm/kfence: remove unnecessary CONFIG_KFENCE optionIn mm/Makefile has: obj-$(CONFIG_KFENCE) += kfence/So that we don't need 'obj-$(CONFIG_KFENCE) :=' in mm/kfence/Makefile,delete it from mm/kfence/Makefile.Link: https://lkml.kernel.org/r/20220221065525.21344-1-tangmeng@uniontech.comSigned-off-by: tangmeng Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitriy Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/mm/kfence/Makefile

bc8fbc5f - kfence: add test suite

Fri, 26 Feb 2021 01:19:31 +0000

kfence: add test suiteAdd KFENCE test suite, testing various error detection scenarios. Makesuse of KUnit for test organization. Since KFENCE's interface to obtainerror reports is via the console, the test verifies that KFENCE outputsexpected reports to the console.[elver@google.com: fix typo in test] Link: https://lkml.kernel.org/r/X9lHQExmHGvETxY4@elver.google.com[elver@google.com: show access type in report] Link: https://lkml.kernel.org/r/20210111091544.3287013-2-elver@google.comLink: https://lkml.kernel.org/r/20201103175841.3495947-9-elver@google.comSigned-off-by: Alexander Potapenko Signed-off-by: Marco Elver Reviewed-by: Dmitry Vyukov Co-developed-by: Alexander Potapenko Reviewed-by: Jann Horn Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christopher Lameter Cc: Dave Hansen Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Hillf Danton Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joern Engel Cc: Jonathan Corbet Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Paul E. McKenney Cc: Pekka Enberg Cc: Peter Zijlstra Cc: SeongJae Park Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/mm/kfence/Makefile

0ce20dd8 - mm: add Kernel Electric-Fence infrastructure

Fri, 26 Feb 2021 01:18:53 +0000

mm: add Kernel Electric-Fence infrastructurePatch series "KFENCE: A low-overhead sampling-based memory safety error detector", v7.This adds the Kernel Electric-Fence (KFENCE) infrastructure. KFENCE is alow-overhead sampling-based memory safety error detector of heapuse-after-free, invalid-free, and out-of-bounds access errors. Thisseries enables KFENCE for the x86 and arm64 architectures, and addsKFENCE hooks to the SLAB and SLUB allocators.KFENCE is designed to be enabled in production kernels, and has nearzero performance overhead. Compared to KASAN, KFENCE trades performancefor precision. The main motivation behind KFENCE's design, is that withenough total uptime KFENCE will detect bugs in code paths not typicallyexercised by non-production test workloads. One way to quickly achieve alarge enough total uptime is when the tool is deployed across a largefleet of machines.KFENCE objects each reside on a dedicated page, at either the left orright page boundaries. The pages to the left and right of the objectpage are "guard pages", whose attributes are changed to a protectedstate, and cause page faults on any attempted access to them. Such pagefaults are then intercepted by KFENCE, which handles the faultgracefully by reporting a memory access error.Guarded allocations are set up based on a sample interval (can be setvia kfence.sample_interval). After expiration of the sample interval,the next allocation through the main allocator (SLAB or SLUB) returns aguarded allocation from the KFENCE object pool. At this point, the timeris reset, and the next allocation is set up after the expiration of theinterval.To enable/disable a KFENCE allocation through the main allocator'sfast-path without overhead, KFENCE relies on static branches via thestatic keys infrastructure. The static branch is toggled to redirect theallocation to KFENCE.The KFENCE memory pool is of fixed size, and if the pool is exhausted nofurther KFENCE allocations occur. The default config is conservativewith only 255 objects, resulting in a pool size of 2 MiB (with 4 KiBpages).We have verified by running synthetic benchmarks (sysbench I/O,hackbench) and production server-workload benchmarks that a kernel withKFENCE (using sample intervals 100-500ms) is performance-neutralcompared to a non-KFENCE baseline kernel.KFENCE is inspired by GWP-ASan [1], a userspace tool with similarproperties. The name "KFENCE" is a homage to the Electric Fence MallocDebugger [2].For more details, see Documentation/dev-tools/kfence.rst added in theseries -- also viewable here: https://raw.githubusercontent.com/google/kasan/kfence/Documentation/dev-tools/kfence.rst[1] http://llvm.org/docs/GwpAsan.html[2] https://linux.die.net/man/3/efenceThis patch (of 9):This adds the Kernel Electric-Fence (KFENCE) infrastructure. KFENCE is alow-overhead sampling-based memory safety error detector of heapuse-after-free, invalid-free, and out-of-bounds access errors.KFENCE is designed to be enabled in production kernels, and has nearzero performance overhead. Compared to KASAN, KFENCE trades performancefor precision. The main motivation behind KFENCE's design, is that withenough total uptime KFENCE will detect bugs in code paths not typicallyexercised by non-production test workloads. One way to quickly achieve alarge enough total uptime is when the tool is deployed across a largefleet of machines.KFENCE objects each reside on a dedicated page, at either the left orright page boundaries. The pages to the left and right of the objectpage are "guard pages", whose attributes are changed to a protectedstate, and cause page faults on any attempted access to them. Such pagefaults are then intercepted by KFENCE, which handles the faultgracefully by reporting a memory access error. To detect out-of-boundswrites to memory within the object's page itself, KFENCE also usespattern-based redzones. The following figure illustrates the pagelayout: ---+-----------+-----------+-----------+-----------+-----------+--- | xxxxxxxxx | O : | xxxxxxxxx | : O | xxxxxxxxx | | xxxxxxxxx | B : | xxxxxxxxx | : B | xxxxxxxxx | | x GUARD x | J : RED- | x GUARD x | RED- : J | x GUARD x | | xxxxxxxxx | E : ZONE | xxxxxxxxx | ZONE : E | xxxxxxxxx | | xxxxxxxxx | C : | xxxxxxxxx | : C | xxxxxxxxx | | xxxxxxxxx | T : | xxxxxxxxx | : T | xxxxxxxxx | ---+-----------+-----------+-----------+-----------+-----------+---Guarded allocations are set up based on a sample interval (can be setvia kfence.sample_interval). After expiration of the sample interval, aguarded allocation from the KFENCE object pool is returned to the mainallocator (SLAB or SLUB). At this point, the timer is reset, and thenext allocation is set up after the expiration of the interval.To enable/disable a KFENCE allocation through the main allocator'sfast-path without overhead, KFENCE relies on static branches via thestatic keys infrastructure. The static branch is toggled to redirect theallocation to KFENCE. To date, we have verified by running syntheticbenchmarks (sysbench I/O, hackbench) that a kernel compiled with KFENCEis performance-neutral compared to the non-KFENCE baseline.For more details, see Documentation/dev-tools/kfence.rst (added later inthe series).[elver@google.com: fix parameter description for kfence_object_start()] Link: https://lkml.kernel.org/r/20201106092149.GA2851373@elver.google.com[elver@google.com: avoid stalling work queue task without allocations] Link: https://lkml.kernel.org/r/CADYN=9J0DQhizAGB0-jz4HOBBh+05kMBXb4c0cXMS7Qi5NAJiw@mail.gmail.com Link: https://lkml.kernel.org/r/20201110135320.3309507-1-elver@google.com[elver@google.com: fix potential deadlock due to wake_up()] Link: https://lkml.kernel.org/r/000000000000c0645805b7f982e4@google.com Link: https://lkml.kernel.org/r/20210104130749.1768991-1-elver@google.com[elver@google.com: add option to use KFENCE without static keys] Link: https://lkml.kernel.org/r/20210111091544.3287013-1-elver@google.com[elver@google.com: add missing copyright and description headers] Link: https://lkml.kernel.org/r/20210118092159.145934-1-elver@google.comLink: https://lkml.kernel.org/r/20201103175841.3495947-2-elver@google.comSigned-off-by: Marco Elver Signed-off-by: Alexander Potapenko Reviewed-by: Dmitry Vyukov Reviewed-by: SeongJae Park Co-developed-by: Marco Elver Reviewed-by: Jann Horn Cc: "H. Peter Anvin" Cc: Paul E. McKenney Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christopher Lameter Cc: Dave Hansen Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Hillf Danton Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Joonsoo Kim Cc: Joern Engel Cc: Kees Cook Cc: Mark Rutland Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/mm/kfence/Makefile

Changes in Makefile

2e08ca18 - kfence: avoid passing -g for test

56eb8e94 - mm/kfence: remove unnecessary CONFIG_KFENCE option

bc8fbc5f - kfence: add test suite

0ce20dd8 - mm: add Kernel Electric-Fence infrastructure