Jason A. Donenfeld d2a02e3c8b lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI ... 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: 6048fdcc5f ("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>		2022-02-04 19:22:32 +01:00
..
alpha	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
arc	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
arm	lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI	2022-02-04 19:22:32 +01:00
arm64	arm64 fixes:	2022-01-29 08:57:22 +02:00
csky	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
h8300	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
hexagon	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
ia64	ia64: make IA64_MCA_RECOVERY bool instead of tristate	2022-01-30 09:56:58 +02:00
m68k	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
microblaze	Kbuild updates for v5.17	2022-01-19 11:15:19 +02:00
mips	pci-v5.17-fixes-2	2022-01-29 19:05:47 +02:00
nds32	Kbuild updates for v5.17	2022-01-19 11:15:19 +02:00
nios2	Kbuild updates for v5.17	2022-01-19 11:15:19 +02:00
openrisc	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
parisc	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
powerpc	powerpc/64s/interrupt: Fix decrementer storm	2022-01-25 16:50:10 +11:00
riscv	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
s390	s390/hypfs: include z/VM guests with access control group set	2022-01-26 18:42:39 +01:00
sh	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
sparc	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
um	virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes	2022-01-18 10:05:48 +02:00
x86	lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI	2022-02-04 19:22:32 +01:00
xtensa	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
.gitignore
Kconfig	Merge branch 'akpm' (patches from Andrew)	2022-01-20 10:41:01 +02:00