kernel/linux.git/arch/arm/lib, branch v5.15.209

ARM: 9321/1: memset: cast the constant byte to unsigned char

2023-11-20T10:08:23+00:00

[ Upstream commit c0e824661f443b8cab3897006c1bbc69fd0e7bc4 ] memset() description in ISO/IEC 9899:1999 (and elsewhere) says: The memset function copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s. The kernel's arm32 memset does not cast c to unsigned char. This results in the following code to produce erroneous output: char a[128]; memset(a, -128, sizeof(a)); This is because gcc will generally emit the following code before it calls memset() : mov r0, r7 mvn r1, #127 ; 0x7f bl 00000000 r1 ends up with 0xffffff80 before being used by memset() and the 'a' array will have -128 once in every four bytes while the other bytes will be set incorrectly to -1 like this (printing the first 8 bytes) : test_module: -128 -1 -1 -1 test_module: -1 -1 -1 -128 The change here is to 'and' r1 with 255 before it is used. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reviewed-by: Ard Biesheuvel Reviewed-by: Linus Walleij Signed-off-by: Kursad Oney Signed-off-by: Russell King (Oracle) Signed-off-by: Sasha Levin

locking/atomic: arm: fix sync ops

2023-07-23T11:46:48+00:00

[ Upstream commit dda5f312bb09e56e7a1c3e3851f2000eb2e9c879 ] The sync_*() ops on arch/arm are defined in terms of the regular bitops with no special handling. This is not correct, as UP kernels elide barriers for the fully-ordered operations, and so the required ordering is lost when such UP kernels are run under a hypervsior on an SMP system. Fix this by defining sync ops with the required barriers. Note: On 32-bit arm, the sync_*() ops are currently only used by Xen, which requires ARMv7, but the semantics can be implemented for ARMv6+. Fixes: e54d2f61528165bb ("xen/arm: sync_bitops") Signed-off-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230605070124.3741859-2-mark.rutland@arm.com Signed-off-by: Sasha Levin

ARM: 9290/1: uaccess: Fix KASAN false-positives

2023-04-20T10:13:54+00:00

[ Upstream commit ceac10c83b330680cc01ceaaab86cd49f4f30d81 ] __copy_to_user_memcpy() and __clear_user_memset() had been calling memcpy() and memset() respectively, leading to false-positive KASAN reports when starting userspace: [ 10.707901] Run /init as init process [ 10.731892] process '/bin/busybox' started with executable stack [ 10.745234] ================================================================== [ 10.745796] BUG: KASAN: user-memory-access in __clear_user_memset+0x258/0x3ac [ 10.747260] Write of size 2687 at addr 000de581 by task init/1 Use __memcpy() and __memset() instead to allow userspace access, which is of course the intent of these functions. Signed-off-by: Andrew Jeffery Signed-off-by: Zev Weiss Reviewed-by: Arnd Bergmann Signed-off-by: Russell King (Oracle) Signed-off-by: Sasha Levin

ARM: findbit: fix overflowing offset

2022-08-17T12:23:05+00:00

[ Upstream commit ec85bd369fd2bfaed6f45dd678706429d4f75b48 ] When offset is larger than the size of the bit array, we should not attempt to access the array as we can perform an access beyond the end of the array. Fix this by changing the pre-condition. Using "cmp r2, r1; bhs ..." covers us for the size == 0 case, since this will always take the branch when r1 is zero, irrespective of the value of r2. This means we can fix this bug without adding any additional code! Tested-by: Guenter Roeck Signed-off-by: Russell King (Oracle) Signed-off-by: Sasha Levin

ARM: crypto: comment out gcc warning that breaks clang builds

2022-08-03T10:03:54+00:00

The gcc build warning prevents all clang-built kernels from working properly, so comment it out to fix the build. This is a -stable kernel only patch for now, it will be resolved differently in mainline releases in the future. Cc: "Jason A. Donenfeld" Cc: "Justin M. Forbes" Cc: Ard Biesheuvel Acked-by: Arnd Bergmann Cc: Nicolas Pitre Cc: Nathan Chancellor Cc: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2021-09-09T20:25:49+00:00

Pull ARM development updates from Russell King: - Rename "mod_init" and "mod_exit" so that initcall debug output is actually useful (Randy Dunlap) - Update maintainers entries for linux-arm-kernel to indicate it is moderated for non-subscribers (Randy Dunlap) - Move install rules to arch/arm/Makefile (Masahiro Yamada) - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij) - Don't warn about atags_to_fdt() stack size (David Heidelberg) - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann) - Get rid of set_fs() usage (Arnd Bergmann) - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven) * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK() ARM: 9116/1: unified: Remove check for gcc < 4 ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning ARM: 9113/1: uaccess: remove set_fs() implementation ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault ARM: 9111/1: oabi-compat: rework fcntl64() emulation ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation ARM: 9107/1: syscall: always store thread_info->abi_syscall ARM: 9109/1: oabi-compat: add epoll_pwait handler ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs() ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault ARM: 9105/1: atags_to_fdt: don't warn about stack size ARM: 9103/1: Drop ARCH_NR_GPIOS definition ARM: 9102/1: move theinstall rules to arch/arm/Makefile ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific

ARM: 9113/1: uaccess: remove set_fs() implementation

2021-08-20T10:39:27+00:00

There are no remaining callers of set_fs(), so just remove it along with all associated code that operates on thread_info->addr_limit. There are still further optimizations that can be done: - In get_user(), the address check could be moved entirely into the out of line code, rather than passing a constant as an argument, - I assume the DACR handling can be simplified as we now only change it during user access when CONFIG_CPU_SW_DOMAIN_PAN is set, but not during set_fs(). Acked-by: Christoph Hellwig Signed-off-by: Arnd Bergmann Signed-off-by: Russell King (Oracle)

printk: Userspace format indexing support

2021-07-19T09:57:48+00:00

We have a number of systems industry-wide that have a subset of their functionality that works as follows: 1. Receive a message from local kmsg, serial console, or netconsole; 2. Apply a set of rules to classify the message; 3. Do something based on this classification (like scheduling a remediation for the machine), rinse, and repeat. As a couple of examples of places we have this implemented just inside Facebook, although this isn't a Facebook-specific problem, we have this inside our netconsole processing (for alarm classification), and as part of our machine health checking. We use these messages to determine fairly important metrics around production health, and it's important that we get them right. While for some kinds of issues we have counters, tracepoints, or metrics with a stable interface which can reliably indicate the issue, in order to react to production issues quickly we need to work with the interface which most kernel developers naturally use when developing: printk. Most production issues come from unexpected phenomena, and as such usually the code in question doesn't have easily usable tracepoints or other counters available for the specific problem being mitigated. We have a number of lines of monitoring defence against problems in production (host metrics, process metrics, service metrics, etc), and where it's not feasible to reliably monitor at another level, this kind of pragmatic netconsole monitoring is essential. As one would expect, monitoring using printk is rather brittle for a number of reasons -- most notably that the message might disappear entirely in a new version of the kernel, or that the message may change in some way that the regex or other classification methods start to silently fail. One factor that makes this even harder is that, under normal operation, many of these messages are never expected to be hit. For example, there may be a rare hardware bug which one wants to detect if it was to ever happen again, but its recurrence is not likely or anticipated. This precludes using something like checking whether the printk in question was printed somewhere fleetwide recently to determine whether the message in question is still present or not, since we don't anticipate that it should be printed anywhere, but still need to monitor for its future presence in the long-term. This class of issue has happened on a number of occasions, causing unhealthy machines with hardware issues to remain in production for longer than ideal. As a recent example, some monitoring around blk_update_request fell out of date and caused semi-broken machines to remain in production for longer than would be desirable. Searching through the codebase to find the message is also extremely fragile, because many of the messages are further constructed beyond their callsite (eg. btrfs_printk and other module-specific wrappers, each with their own functionality). Even if they aren't, guessing the format and formulation of the underlying message based on the aesthetics of the message emitted is not a recipe for success at scale, and our previous issues with fleetwide machine health checking demonstrate as much. This provides a solution to the issue of silently changed or deleted printks: we record pointers to all printk format strings known at compile time into a new .printk_index section, both in vmlinux and modules. At runtime, this can then be iterated by looking at /printk/index/, which emits the following format, both readable by humans and able to be parsed by machines: $ head -1 vmlinux; shuf -n 5 vmlinux # filename:line function "format" <5> block/blk-settings.c:661 disk_stack_limits "%s: Warning: Device %s is misaligned\n" <4> kernel/trace/trace.c:8296 trace_create_file "Could not create tracefs '%s' entry\n" <6> arch/x86/kernel/hpet.c:144 _hpet_print_config "hpet: %s(%d):\n" <6> init/do_mounts.c:605 prepare_namespace "Waiting for root device %s...\n" <6> drivers/acpi/osl.c:1410 acpi_no_auto_serialize_setup "ACPI: auto-serialization disabled\n" This mitigates the majority of cases where we have a highly-specific printk which we want to match on, as we can now enumerate and check whether the format changed or the printk callsite disappeared entirely in userspace. This allows us to catch changes to printks we monitor earlier and decide what to do about it before it becomes problematic. There is no additional runtime cost for printk callers or printk itself, and the assembly generated is exactly the same. Signed-off-by: Chris Down Cc: Petr Mladek Cc: Jessica Yu Cc: Sergey Senozhatsky Cc: John Ogness Cc: Steven Rostedt Cc: Greg Kroah-Hartman Cc: Johannes Weiner Cc: Kees Cook Reviewed-by: Petr Mladek Tested-by: Petr Mladek Reported-by: kernel test robot Acked-by: Andy Shevchenko Acked-by: Jessica Yu # for module.{c,h} Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/e42070983637ac5e384f17fbdbe86d19c7b212a5.1623775748.git.chris@chrisdown.name

ARM: 9022/1: Change arch/arm/lib/mem*.S to use WEAK instead of .weak

2020-11-12T14:53:19+00:00

Commit d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan") add .weak directives to memcpy/memmove/memset to avoid collision with KASAN interceptors. This does not work with LLVM's integrated assembler (the assembly snippet `.weak memcpy ... .globl memcpy` produces a STB_GLOBAL memcpy while GNU as produces a STB_WEAK memcpy). LLVM 12 (since https://reviews.llvm.org/D90108) will error on such an overridden symbol binding. Use the appropriate WEAK macro instead. Link: https://github.com/ClangBuiltLinux/linux/issues/1190 -- Fixes: d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan") Reported-by: Nick Desaulniers Signed-off-by: Fangrui Song Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Signed-off-by: Russell King

ARM: 9014/2: Replace string mem* functions for KASan

2020-10-27T12:11:06+00:00

Functions like memset()/memmove()/memcpy() do a lot of memory accesses. If a bad pointer is passed to one of these functions it is important to catch this. Compiler instrumentation cannot do this since these functions are written in assembly. KASan replaces these memory functions with instrumented variants. The original functions are declared as weak symbols so that the strong definitions in mm/kasan/kasan.c can replace them. The original functions have aliases with a '__' prefix in their name, so we can call the non-instrumented variant if needed. We must use __memcpy()/__memset() in place of memcpy()/memset() when we copy .data to RAM and when we clear .bss, because kasan_early_init cannot be called before the initialization of .data and .bss. For the kernel compression and EFI libstub's custom string libraries we need a special quirk: even if these are built without KASan enabled, they rely on the global headers for their custom string libraries, which means that e.g. memcpy() will be defined to __memcpy() and we get link failures. Since these implementations are written i C rather than assembly we use e.g. __alias(memcpy) to redirected any users back to the local implementation. Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli # Brahma SoCs Tested-by: Ahmad Fatoum # i.MX6Q Reported-by: Russell King - ARM Linux Signed-off-by: Ahmad Fatoum Signed-off-by: Abbott Liu Signed-off-by: Florian Fainelli Signed-off-by: Linus Walleij Signed-off-by: Russell King