This is a note to let you know that I've just added the patch titled random: skip fast_init if hwrng provides large chunk of entropy to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: random-skip-fast_init-if-hwrng-provides-large-chunk-of-entropy.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Jun 16 07:08:33 PM CEST 2022 From: "Jason A. Donenfeld" <Jason@xxxxxxxxx> Date: Mon, 21 Mar 2022 18:48:05 -0600 Subject: random: skip fast_init if hwrng provides large chunk of entropy From: "Jason A. Donenfeld" <Jason@xxxxxxxxx> commit af704c856e888fb044b058d731d61b46eeec499d upstream. At boot time, EFI calls add_bootloader_randomness(), which in turn calls add_hwgenerator_randomness(). Currently add_hwgenerator_randomness() feeds the first 64 bytes of randomness to the "fast init" non-crypto-grade phase. But if add_hwgenerator_randomness() gets called with more than POOL_MIN_BITS of entropy, there's no point in passing it off to the "fast init" stage, since that's enough entropy to bootstrap the real RNG. The "fast init" stage is just there to provide _something_ in the case where we don't have enough entropy to properly bootstrap the RNG. But if we do have enough entropy to bootstrap the RNG, the current logic doesn't serve a purpose. So, in the case where we're passed greater than or equal to POOL_MIN_BITS of entropy, this commit makes us skip the "fast init" phase. Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/char/random.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1120,7 +1120,7 @@ void rand_initialize_disk(struct gendisk void add_hwgenerator_randomness(const void *buffer, size_t count, size_t entropy) { - if (unlikely(crng_init == 0)) { + if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) { size_t ret = crng_pre_init_inject(buffer, count, true); mix_pool_bytes(buffer, ret); count -= ret; Patches currently in stable-queue which might be from Jason@xxxxxxxxx are queue-4.14/random-do-not-take-pool-spinlock-at-boot.patch queue-4.14/random-remove-kernel.random.read_wakeup_threshold.patch queue-4.14/random-simplify-arithmetic-function-flow-in-account.patch queue-4.14/random-order-timer-entropy-functions-below-interrupt-functions.patch queue-4.14/random-introduce-drain_entropy-helper-to-declutter-crng_reseed.patch queue-4.14/random-fix-locking-in-crng_fast_load.patch queue-4.14/random-cleanup-uuid-handling.patch queue-4.14/random-group-userspace-read-write-functions.patch queue-4.14/random-make-credit_entropy_bits-always-safe.patch queue-4.14/latent_entropy-avoid-build-error-when-plugin-cflags-are-not-set.patch queue-4.14/revert-hwrng-core-freeze-khwrng-thread-during-suspend.patch queue-4.14/drivers-char-random.c-make-primary_crng-static.patch queue-4.14/random-do-not-re-init-if-crng_reseed-completes-before-primary-init.patch queue-4.14/random-always-fill-buffer-in-get_random_bytes_wait.patch queue-4.14/random-use-proper-jiffies-comparison-macro.patch queue-4.14/init-call-time_init-before-rand_initialize.patch queue-4.14/random-split-primary-secondary-crng-init-paths.patch queue-4.14/random-pull-add_hwgenerator_randomness-declaration-into-random.h.patch queue-4.14/random-unify-early-init-crng-load-accounting.patch queue-4.14/drivers-char-random.c-remove-unused-stuct-poolinfo-poolbits.patch queue-4.14/random-use-blake2s-instead-of-sha1-in-extraction.patch queue-4.14/random-make-cpu-trust-a-boot-parameter.patch queue-4.14/random-convert-to-using-fops-write_iter.patch queue-4.14/random-initialize-chacha20-constants-with-correct-endianness.patch queue-4.14/random-remove-incomplete-last_data-logic.patch queue-4.14/random-group-entropy-extraction-functions.patch queue-4.14/random-optimize-add_interrupt_randomness.patch queue-4.14/random-add-proper-spdx-header.patch queue-4.14/linux-random.h-remove-arch_has_random-arch_has_random_seed.patch queue-4.14/random-rewrite-header-introductory-comment.patch queue-4.14/random-make-dev-random-be-almost-like-dev-urandom.patch queue-4.14/random-remove-ifdef-d-out-interrupt-bench.patch queue-4.14/um-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/lib-crypto-sha1-re-roll-loops-to-reduce-code-size.patch queue-4.14/random-tie-batched-entropy-generation-to-base_crng-generation.patch queue-4.14/sparc-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/random-use-linear-min-entropy-accumulation-crediting.patch queue-4.14/random-remove-batched-entropy-locking.patch queue-4.14/xtensa-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/powerpc-remove-arch_has_random-arch_has_random_seed.patch queue-4.14/fdt-add-support-for-rng-seed.patch queue-4.14/random-continually-use-hwgenerator-randomness.patch queue-4.14/random-access-input_pool_data-directly-rather-than-through-pointer.patch queue-4.14/random-add-arch_get_random_-long_early.patch queue-4.14/random-inline-leaves-of-rand_initialize.patch queue-4.14/random-cleanup-poolinfo-abstraction.patch queue-4.14/random-wire-up-fops-splice_-read-write-_iter.patch queue-4.14/random-handle-latent-entropy-and-command-line-from-random_init.patch queue-4.14/random-remove-use_input_pool-parameter-from-crng_reseed.patch queue-4.14/random-credit-architectural-init-the-exact-amount.patch queue-4.14/ia64-define-get_cycles-macro-for-arch-override.patch queue-4.14/random-replace-custom-notifier-chain-with-standard-one.patch queue-4.14/random-support-freezable-kthreads-in-add_hwgenerator_randomness.patch queue-4.14/random-document-get_random_int-family.patch queue-4.14/random-remove-the-blocking-pool.patch queue-4.14/random-avoid-initializing-twice-in-credit-race.patch queue-4.14/random-avoid-warnings-for-config_numa-builds.patch queue-4.14/crypto-drbg-add-fips-140-2-ctrng-for-noise-source.patch queue-4.14/random-mark-bootloader-randomness-code-as-__init.patch queue-4.14/random-zero-buffer-after-reading-entropy-from-userspace.patch queue-4.14/random-remove-whitespace-and-reorder-includes.patch queue-4.14/random-ignore-grnd_random-in-getentropy-2.patch queue-4.14/random-clear-fast-pool-crng-and-batches-in-cpuhp-bring-up.patch queue-4.14/random-document-add_hwgenerator_randomness-with-other-input-functions.patch queue-4.14/random-fix-typo-in-add_timer_randomness.patch queue-4.14/random-do-crng-pre-init-loading-in-worker-rather-than-irq.patch queue-4.14/powerpc-use-bool-in-archrandom.h.patch queue-4.14/random-do-not-split-fast-init-input-in-add_hwgenerator_randomness.patch queue-4.14/timekeeping-add-raw-clock-fallback-for-random_get_entropy.patch queue-4.14/random-early-initialization-of-chacha-constants.patch queue-4.14/crypto-drbg-prepare-for-more-fine-grained-tracking-of-seeding-state.patch queue-4.14/random-delete-code-to-pull-data-into-pools.patch queue-4.14/crypto-drbg-always-try-to-free-jitter-rng-instance.patch queue-4.14/random-simplify-entropy-debiting.patch queue-4.14/random-don-t-reset-crng_init_cnt-on-urandom_read.patch queue-4.14/random-skip-fast_init-if-hwrng-provides-large-chunk-of-entropy.patch queue-4.14/random-use-siphash-as-interrupt-entropy-accumulator.patch queue-4.14/random-avoid-checking-crng_ready-twice-in-random_init.patch queue-4.14/random-fix-soft-lockup-when-trying-to-read-from-an-uninitialized-blocking-pool.patch queue-4.14/random-group-sysctl-functions.patch queue-4.14/random-don-t-let-644-read-only-sysctls-be-written-to.patch queue-4.14/random-document-crng_fast_key_erasure-destination-possibility.patch queue-4.14/random-only-wake-up-writers-after-zap-if-threshold-was-passed.patch queue-4.14/random-use-wait_event_freezable-in-add_hwgenerator_randomness.patch queue-4.14/random-check-for-signal-and-try-earlier-when-generating-entropy.patch queue-4.14/random-check-for-signals-every-page_size-chunk-of-dev-random.patch queue-4.14/arm-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/random-absorb-fast-pool-into-input-pool-after-fast-load.patch queue-4.14/random-give-sysctl_random_min_urandom_seed-a-more-sensible-value.patch queue-4.14/crypto-blake2s-generic-c-library-implementation-and-selftest.patch queue-4.14/random-cleanup-fractional-entropy-shift-constants.patch queue-4.14/random-use-rdseed-instead-of-rdrand-in-entropy-extraction.patch queue-4.14/random-move-rand_initialize-earlier.patch queue-4.14/random-don-t-wake-crng_init_wait-when-crng_init-1.patch queue-4.14/random-add-a-urandom_read_nowait-for-random-apis-that-don-t-warn.patch queue-4.14/random-do-not-sign-extend-bytes-for-rotation-when-mixing.patch queue-4.14/random-move-initialization-functions-out-of-hot-pages.patch queue-4.14/random-remove-dead-code-left-over-from-blocking-pool.patch queue-4.14/drivers-char-random.c-constify-poolinfo_table.patch queue-4.14/crypto-drbg-track-whether-drbg-was-seeded-with-rng_is_initialized.patch queue-4.14/random-use-computational-hash-for-entropy-extraction.patch queue-4.14/random-add-and-use-pr_fmt.patch queue-4.14/random-round-robin-registers-as-ulong-not-u32.patch queue-4.14/random-always-wake-up-entropy-writers-after-extraction.patch queue-4.14/s390-remove-arch_has_random-arch_has_random_seed.patch queue-4.14/random-do-not-xor-rdrand-when-writing-into-dev-random.patch queue-4.14/crypto-drbg-make-reseeding-from-get_random_bytes-synchronous.patch queue-4.14/random-convert-to-entropy_bits-for-better-code-readability.patch queue-4.14/char-random-add-a-newline-at-the-end-of-the-file.patch queue-4.14/random-move-randomize_page-into-mm-where-it-belongs.patch queue-4.14/random-only-call-crng_finalize_init-for-primary_crng.patch queue-4.14/random-cleanup-integer-types.patch queue-4.14/random-re-add-removed-comment-about-get_random_-u32-u64-reseeding.patch queue-4.14/random-unify-cycles_t-and-jiffies-usage-and-types.patch queue-4.14/random-insist-on-random_get_entropy-existing-in-order-to-simplify.patch queue-4.14/random-group-initialization-wait-functions.patch queue-4.14/linux-random.h-mark-config_arch_random-functions-__must_check.patch queue-4.14/random-remove-unused-extract_entropy-reserved-argument.patch queue-4.14/random-check-for-signal_pending-outside-of-need_resched-check.patch queue-4.14/random-access-primary_pool-directly-rather-than-through-pointer.patch queue-4.14/random-fix-sysctl-documentation-nits.patch queue-4.14/random-remove-unused-tracepoints.patch queue-4.14/random-only-read-from-dev-random-after-its-pool-has-received-128-bits.patch queue-4.14/nios2-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/random-treat-bootloader-trust-toggle-the-same-way-as-cpu-trust-toggle.patch queue-4.14/random-make-consistent-usage-of-crng_ready.patch queue-4.14/lib-crypto-blake2s-move-hmac-construction-into-wireguard.patch queue-4.14/parisc-define-get_cycles-macro-for-arch-override.patch queue-4.14/x86-tsc-use-fallback-for-random_get_entropy-instead-of-zero.patch queue-4.14/crypto-chacha20-fix-keystream-alignment-for-chacha20_block.patch queue-4.14/random-add-grnd_insecure-to-return-best-effort-non-cryptographic-bytes.patch queue-4.14/random-fix-whitespace-pre-random-bytes-work.patch queue-4.14/crypto-drbg-move-dynamic-reseed_threshold-adjustments-to-__drbg_seed.patch queue-4.14/random-check-for-signals-after-page-of-pool-writes.patch queue-4.14/random-make-random_get_entropy-return-an-unsigned-long.patch queue-4.14/random-check-for-crng_init-0-in-add_device_randomness.patch queue-4.14/random-add-a-config-option-to-trust-the-cpu-s-hwrng.patch queue-4.14/random-remove-unnecessary-unlikely.patch queue-4.14/random-defer-fast-pool-mixing-to-worker.patch queue-4.14/random-harmonize-crng-init-done-messages.patch queue-4.14/crypto-blake2s-include-linux-bug.h-instead-of-asm-bug.h.patch queue-4.14/random-use-static-branch-for-crng_ready.patch queue-4.14/random-rather-than-entropy_store-abstraction-use-global.patch queue-4.14/drivers-char-random.c-remove-unused-dont_count_entropy.patch queue-4.14/random-remove-extern-from-functions-in-header.patch queue-4.14/siphash-use-one-source-of-truth-for-siphash-permutations.patch 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queue-4.14/random-avoid-arch_get_random_seed_long-when-collecting-irq-randomness.patch queue-4.14/random-use-is_enabled-config_numa-instead-of-ifdefs.patch queue-4.14/random-make-crng-state-queryable.patch queue-4.14/random-avoid-superfluous-call-to-rdrand-in-crng-extraction.patch queue-4.14/random-use-symbolic-constants-for-crng_init-states.patch queue-4.14/random-reseed-more-often-immediately-after-booting.patch queue-4.14/random-ensure-early-rdseed-goes-through-mixer-on-init.patch queue-4.14/random-deobfuscate-irq-u32-u64-contributions.patch queue-4.14/random-do-not-use-input-pool-from-hard-irqs.patch queue-4.14/random-help-compiler-out-with-fast_mix-by-using-simpler-arguments.patch queue-4.14/revert-random-use-static-branch-for-crng_ready.patch queue-4.14/random-fix-crash-on-multiple-early-calls-to-add_bootloader_randomness.patch queue-4.14/random-return-nbytes-filled-from-hw-rng.patch queue-4.14/random-account-for-arch-randomness-in-bits.patch queue-4.14/crypto-blake2s-adjust-include-guard-naming.patch queue-4.14/random-do-not-allow-user-to-keep-crng-key-around-on-stack.patch queue-4.14/x86-remove-arch_has_random-arch_has_random_seed.patch queue-4.14/crypto-deduplicate-le32_to_cpu_array-and-cpu_to_le32_array.patch queue-4.14/random-remove-ratelimiting-for-in-kernel-unseeded-randomness.patch queue-4.14/random-remove-unused-irq_flags-argument-from-add_interrupt_randomness.patch queue-4.14/random-prepend-remaining-pool-constants-with-pool_.patch queue-4.14/powerpc-define-get_cycles-macro-for-arch-override.patch queue-4.14/random-remove-unused-output_pool-constants.patch queue-4.14/mips-use-fallback-for-random_get_entropy-instead-of-just-c0-random.patch queue-4.14/random-use-hash-function-for-crng_slow_load.patch queue-4.14/random-fix-typo-in-comments.patch queue-4.14/random-remove-preempt-disabled-region.patch queue-4.14/random-use-proper-return-types-on-get_random_-int-long-_wait.patch