kernel_optimize_test/arch
Jason A. Donenfeld ae33c501e0 lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI
commit d2a02e3c8bb6b347818518edff5a4b40ff52d6d8 upstream.

blake2s_compress_generic is weakly aliased by blake2s_compress. The
current harness for function selection uses a function pointer, which is
ordinarily inlined and resolved at compile time. But when Clang's CFI is
enabled, CFI still triggers when making an indirect call via a weak
symbol. This seems like a bug in Clang's CFI, as though it's bucketing
weak symbols and strong symbols differently. It also only seems to
trigger when "full LTO" mode is used, rather than "thin LTO".

[    0.000000][    T0] Kernel panic - not syncing: CFI failure (target: blake2s_compress_generic+0x0/0x1444)
[    0.000000][    T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.16.0-mainline-06981-g076c855b846e #1
[    0.000000][    T0] Hardware name: MT6873 (DT)
[    0.000000][    T0] Call trace:
[    0.000000][    T0]  dump_backtrace+0xfc/0x1dc
[    0.000000][    T0]  dump_stack_lvl+0xa8/0x11c
[    0.000000][    T0]  panic+0x194/0x464
[    0.000000][    T0]  __cfi_check_fail+0x54/0x58
[    0.000000][    T0]  __cfi_slowpath_diag+0x354/0x4b0
[    0.000000][    T0]  blake2s_update+0x14c/0x178
[    0.000000][    T0]  _extract_entropy+0xf4/0x29c
[    0.000000][    T0]  crng_initialize_primary+0x24/0x94
[    0.000000][    T0]  rand_initialize+0x2c/0x6c
[    0.000000][    T0]  start_kernel+0x2f8/0x65c
[    0.000000][    T0]  __primary_switched+0xc4/0x7be4
[    0.000000][    T0] Rebooting in 5 seconds..

Nonetheless, the function pointer method isn't so terrific anyway, so
this patch replaces it with a simple boolean, which also gets inlined
away. This successfully works around the Clang bug.

In general, I'm not too keen on all of the indirection involved here; it
clearly does more harm than good. Hopefully the whole thing can get
cleaned up down the road when lib/crypto is overhauled more
comprehensively. But for now, we go with a simple bandaid.

Fixes: 6048fdcc5f26 ("lib/crypto: blake2s: include as built-in")
Link: https://github.com/ClangBuiltLinux/linux/issues/1567
Reported-by: Miles Chen <miles.chen@mediatek.com>
Tested-by: Miles Chen <miles.chen@mediatek.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-30 09:33:26 +02:00
..
alpha alpha: Declare virt_to_phys and virt_to_bus parameter as pointer to volatile 2021-09-30 10:11:07 +02:00
arc ARC: entry: fix syscall_trace_exit argument 2022-04-27 13:53:55 +02:00
arm ARM: 9197/1: spectre-bhb: fix loop8 sequence for Thumb2 2022-05-25 09:17:59 +02:00
arm64 arm64: Enable repeat tlbi workaround on KRYO4XX gold CPUs 2022-05-25 09:18:01 +02:00
c6x
csky uaccess: fix type mismatch warnings from access_ok() 2022-04-08 14:40:35 +02:00
h8300
hexagon hexagon: clean up timer-regs.h 2021-11-26 10:39:19 +01:00
ia64 ia64: ensure proper NUMA distance and possible map initialization 2022-03-08 19:09:34 +01:00
m68k m68k: coldfire/device.c: only build for MCF_EDMA when h/w macros are defined 2022-04-08 14:40:09 +02:00
microblaze uaccess: fix nios2 and microblaze get_user_8() 2022-04-08 14:40:08 +02:00
mips MIPS: lantiq: check the return value of kzalloc() 2022-05-25 09:17:54 +02:00
nds32 nds32: fix access_ok() checks in get/put_user 2022-03-28 09:57:10 +02:00
nios2 uaccess: fix type mismatch warnings from access_ok() 2022-04-08 14:40:35 +02:00
openrisc openrisc: Add clone3 ABI wrapper 2022-01-27 10:54:06 +01:00
parisc parisc: Merge model and model name into one line in /proc/cpuinfo 2022-05-12 12:25:29 +02:00
powerpc powerpc/perf: Fix 32bit compile 2022-05-09 09:05:06 +02:00
riscv riscv: dts: sifive: fu540-c000: align dma node name with dtschema 2022-05-25 09:17:59 +02:00
s390 s390/pci: improve zpci_dev reference counting 2022-05-25 09:17:53 +02:00
sh sh: define __BIG_ENDIAN for math-emu 2021-11-26 10:39:12 +01:00
sparc uaccess: fix type mismatch warnings from access_ok() 2022-04-08 14:40:35 +02:00
um um: Fix uml_mconsole stop/go 2022-04-08 14:40:44 +02:00
x86 lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-05-30 09:33:26 +02:00
xtensa xtensa: fix a7 clobbering in coprocessor context load/store 2022-04-27 13:53:55 +02:00
.gitignore
Kconfig arch/cc: Introduce a function to check for confidential computing features 2021-11-18 14:04:32 +01:00