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d2a02e3c8b
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>
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR MIT
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/*
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* shash interface to the generic implementation of BLAKE2s
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*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*/
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#include <crypto/internal/blake2s.h>
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#include <crypto/internal/hash.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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static int crypto_blake2s_update_generic(struct shash_desc *desc,
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const u8 *in, unsigned int inlen)
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{
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return crypto_blake2s_update(desc, in, inlen, true);
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}
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static int crypto_blake2s_final_generic(struct shash_desc *desc, u8 *out)
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{
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return crypto_blake2s_final(desc, out, true);
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}
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#define BLAKE2S_ALG(name, driver_name, digest_size) \
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{ \
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.base.cra_name = name, \
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.base.cra_driver_name = driver_name, \
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.base.cra_priority = 100, \
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.base.cra_flags = CRYPTO_ALG_OPTIONAL_KEY, \
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.base.cra_blocksize = BLAKE2S_BLOCK_SIZE, \
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.base.cra_ctxsize = sizeof(struct blake2s_tfm_ctx), \
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.base.cra_module = THIS_MODULE, \
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.digestsize = digest_size, \
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.setkey = crypto_blake2s_setkey, \
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.init = crypto_blake2s_init, \
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.update = crypto_blake2s_update_generic, \
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.final = crypto_blake2s_final_generic, \
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.descsize = sizeof(struct blake2s_state), \
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}
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static struct shash_alg blake2s_algs[] = {
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BLAKE2S_ALG("blake2s-128", "blake2s-128-generic",
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BLAKE2S_128_HASH_SIZE),
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BLAKE2S_ALG("blake2s-160", "blake2s-160-generic",
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BLAKE2S_160_HASH_SIZE),
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BLAKE2S_ALG("blake2s-224", "blake2s-224-generic",
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BLAKE2S_224_HASH_SIZE),
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BLAKE2S_ALG("blake2s-256", "blake2s-256-generic",
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BLAKE2S_256_HASH_SIZE),
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};
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static int __init blake2s_mod_init(void)
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{
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return crypto_register_shashes(blake2s_algs, ARRAY_SIZE(blake2s_algs));
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}
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static void __exit blake2s_mod_exit(void)
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{
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crypto_unregister_shashes(blake2s_algs, ARRAY_SIZE(blake2s_algs));
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}
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subsys_initcall(blake2s_mod_init);
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module_exit(blake2s_mod_exit);
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MODULE_ALIAS_CRYPTO("blake2s-128");
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MODULE_ALIAS_CRYPTO("blake2s-128-generic");
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MODULE_ALIAS_CRYPTO("blake2s-160");
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MODULE_ALIAS_CRYPTO("blake2s-160-generic");
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MODULE_ALIAS_CRYPTO("blake2s-224");
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MODULE_ALIAS_CRYPTO("blake2s-224-generic");
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MODULE_ALIAS_CRYPTO("blake2s-256");
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MODULE_ALIAS_CRYPTO("blake2s-256-generic");
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MODULE_LICENSE("GPL v2");
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