This is a note to let you know that I've just added the patch titled
random: document crng_fast_key_erasure() destination possibility
to the 4.19-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-document-crng_fast_key_erasure-destination-possibility.patch
and it can be found in the queue-4.19 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 Fri Jun 17 08:58:56 AM CEST 2022
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Date: Mon, 18 Apr 2022 20:57:31 +0200
Subject: random: document crng_fast_key_erasure() destination possibility
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
commit 8717627d6ac53251ee012c3c7aca392f29f38a42 upstream.
This reverts 35a33ff3807d ("random: use memmove instead of memcpy for
remaining 32 bytes"), which was made on a totally bogus basis. The thing
it was worried about overlapping came from the stack, not from one of
its arguments, as Eric pointed out.
But the fact that this confusion even happened draws attention to the
fact that it's a bit non-obvious that the random_data parameter can
alias chacha_state, and in fact should do so when the caller can't rely
on the stack being cleared in a timely manner. So this commit documents
that.
Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/random.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -318,6 +318,13 @@ static void crng_reseed(void)
* the resultant ChaCha state to the user, along with the second
* half of the block containing 32 bytes of random data that may
* be used; random_data_len may not be greater than 32.
+ *
+ * The returned ChaCha state contains within it a copy of the old
+ * key value, at index 4, so the state should always be zeroed out
+ * immediately after using in order to maintain forward secrecy.
+ * If the state cannot be erased in a timely manner, then it is
+ * safer to set the random_data parameter to &chacha_state[4] so
+ * that this function overwrites it before returning.
*/
static void crng_fast_key_erasure(u8 key[CHACHA20_KEY_SIZE],
u32 chacha_state[CHACHA20_BLOCK_SIZE / sizeof(u32)],
Patches currently in stable-queue which might be from Jason@xxxxxxxxx are
queue-4.19/random-do-not-take-pool-spinlock-at-boot.patch
queue-4.19/random-remove-kernel.random.read_wakeup_threshold.patch
queue-4.19/random-simplify-arithmetic-function-flow-in-account.patch
queue-4.19/random-order-timer-entropy-functions-below-interrupt-functions.patch
queue-4.19/random-introduce-drain_entropy-helper-to-declutter-crng_reseed.patch
queue-4.19/random-fix-locking-in-crng_fast_load.patch
queue-4.19/random-cleanup-uuid-handling.patch
queue-4.19/random-group-userspace-read-write-functions.patch
queue-4.19/random-make-credit_entropy_bits-always-safe.patch
queue-4.19/latent_entropy-avoid-build-error-when-plugin-cflags-are-not-set.patch
queue-4.19/revert-hwrng-core-freeze-khwrng-thread-during-suspend.patch
queue-4.19/drivers-char-random.c-make-primary_crng-static.patch
queue-4.19/random-do-not-re-init-if-crng_reseed-completes-before-primary-init.patch
queue-4.19/random-use-proper-jiffies-comparison-macro.patch
queue-4.19/init-call-time_init-before-rand_initialize.patch
queue-4.19/random-split-primary-secondary-crng-init-paths.patch
queue-4.19/random-pull-add_hwgenerator_randomness-declaration-into-random.h.patch
queue-4.19/random-unify-early-init-crng-load-accounting.patch
queue-4.19/drivers-char-random.c-remove-unused-stuct-poolinfo-poolbits.patch
queue-4.19/random-use-blake2s-instead-of-sha1-in-extraction.patch
queue-4.19/random-convert-to-using-fops-write_iter.patch
queue-4.19/random-initialize-chacha20-constants-with-correct-endianness.patch
queue-4.19/random-remove-incomplete-last_data-logic.patch
queue-4.19/random-group-entropy-extraction-functions.patch
queue-4.19/random-add-proper-spdx-header.patch
queue-4.19/linux-random.h-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-rewrite-header-introductory-comment.patch
queue-4.19/random-make-dev-random-be-almost-like-dev-urandom.patch
queue-4.19/random-remove-ifdef-d-out-interrupt-bench.patch
queue-4.19/um-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/lib-crypto-sha1-re-roll-loops-to-reduce-code-size.patch
queue-4.19/random-tie-batched-entropy-generation-to-base_crng-generation.patch
queue-4.19/sparc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-use-linear-min-entropy-accumulation-crediting.patch
queue-4.19/random-remove-batched-entropy-locking.patch
queue-4.19/xtensa-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/powerpc-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/fdt-add-support-for-rng-seed.patch
queue-4.19/random-continually-use-hwgenerator-randomness.patch
queue-4.19/random-access-input_pool_data-directly-rather-than-through-pointer.patch
queue-4.19/random-add-arch_get_random_-long_early.patch
queue-4.19/random-inline-leaves-of-rand_initialize.patch
queue-4.19/random-cleanup-poolinfo-abstraction.patch
queue-4.19/random-wire-up-fops-splice_-read-write-_iter.patch
queue-4.19/random-handle-latent-entropy-and-command-line-from-random_init.patch
queue-4.19/random-remove-use_input_pool-parameter-from-crng_reseed.patch
queue-4.19/random-credit-architectural-init-the-exact-amount.patch
queue-4.19/ia64-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-replace-custom-notifier-chain-with-standard-one.patch
queue-4.19/random-support-freezable-kthreads-in-add_hwgenerator_randomness.patch
queue-4.19/random-document-get_random_int-family.patch
queue-4.19/random-remove-the-blocking-pool.patch
queue-4.19/random-avoid-initializing-twice-in-credit-race.patch
queue-4.19/random-avoid-warnings-for-config_numa-builds.patch
queue-4.19/crypto-drbg-add-fips-140-2-ctrng-for-noise-source.patch
queue-4.19/random-mark-bootloader-randomness-code-as-__init.patch
queue-4.19/random-zero-buffer-after-reading-entropy-from-userspace.patch
queue-4.19/random-remove-whitespace-and-reorder-includes.patch
queue-4.19/random-ignore-grnd_random-in-getentropy-2.patch
queue-4.19/random-clear-fast-pool-crng-and-batches-in-cpuhp-bring-up.patch
queue-4.19/random-document-add_hwgenerator_randomness-with-other-input-functions.patch
queue-4.19/random-fix-typo-in-add_timer_randomness.patch
queue-4.19/random-do-crng-pre-init-loading-in-worker-rather-than-irq.patch
queue-4.19/powerpc-use-bool-in-archrandom.h.patch
queue-4.19/random-do-not-split-fast-init-input-in-add_hwgenerator_randomness.patch
queue-4.19/timekeeping-add-raw-clock-fallback-for-random_get_entropy.patch
queue-4.19/random-early-initialization-of-chacha-constants.patch
queue-4.19/crypto-drbg-prepare-for-more-fine-grained-tracking-of-seeding-state.patch
queue-4.19/random-delete-code-to-pull-data-into-pools.patch
queue-4.19/crypto-drbg-always-try-to-free-jitter-rng-instance.patch
queue-4.19/random-simplify-entropy-debiting.patch
queue-4.19/random-don-t-reset-crng_init_cnt-on-urandom_read.patch
queue-4.19/random-skip-fast_init-if-hwrng-provides-large-chunk-of-entropy.patch
queue-4.19/random-use-siphash-as-interrupt-entropy-accumulator.patch
queue-4.19/random-avoid-checking-crng_ready-twice-in-random_init.patch
queue-4.19/random-fix-soft-lockup-when-trying-to-read-from-an-uninitialized-blocking-pool.patch
queue-4.19/random-group-sysctl-functions.patch
queue-4.19/random-don-t-let-644-read-only-sysctls-be-written-to.patch
queue-4.19/random-document-crng_fast_key_erasure-destination-possibility.patch
queue-4.19/random-only-wake-up-writers-after-zap-if-threshold-was-passed.patch
queue-4.19/random-use-wait_event_freezable-in-add_hwgenerator_randomness.patch
queue-4.19/random-check-for-signal-and-try-earlier-when-generating-entropy.patch
queue-4.19/random-check-for-signals-every-page_size-chunk-of-dev-random.patch
queue-4.19/arm-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-absorb-fast-pool-into-input-pool-after-fast-load.patch
queue-4.19/random-give-sysctl_random_min_urandom_seed-a-more-sensible-value.patch
queue-4.19/crypto-blake2s-generic-c-library-implementation-and-selftest.patch
queue-4.19/random-cleanup-fractional-entropy-shift-constants.patch
queue-4.19/random-use-rdseed-instead-of-rdrand-in-entropy-extraction.patch
queue-4.19/random-move-rand_initialize-earlier.patch
queue-4.19/random-don-t-wake-crng_init_wait-when-crng_init-1.patch
queue-4.19/random-add-a-urandom_read_nowait-for-random-apis-that-don-t-warn.patch
queue-4.19/random-do-not-sign-extend-bytes-for-rotation-when-mixing.patch
queue-4.19/random-move-initialization-functions-out-of-hot-pages.patch
queue-4.19/random-remove-dead-code-left-over-from-blocking-pool.patch
queue-4.19/drivers-char-random.c-constify-poolinfo_table.patch
queue-4.19/crypto-drbg-track-whether-drbg-was-seeded-with-rng_is_initialized.patch
queue-4.19/random-use-computational-hash-for-entropy-extraction.patch
queue-4.19/random-add-and-use-pr_fmt.patch
queue-4.19/random-round-robin-registers-as-ulong-not-u32.patch
queue-4.19/random-always-wake-up-entropy-writers-after-extraction.patch
queue-4.19/s390-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-do-not-xor-rdrand-when-writing-into-dev-random.patch
queue-4.19/crypto-drbg-make-reseeding-from-get_random_bytes-synchronous.patch
queue-4.19/random-convert-to-entropy_bits-for-better-code-readability.patch
queue-4.19/char-random-add-a-newline-at-the-end-of-the-file.patch
queue-4.19/random-move-randomize_page-into-mm-where-it-belongs.patch
queue-4.19/random-only-call-crng_finalize_init-for-primary_crng.patch
queue-4.19/random-cleanup-integer-types.patch
queue-4.19/random-re-add-removed-comment-about-get_random_-u32-u64-reseeding.patch
queue-4.19/random-unify-cycles_t-and-jiffies-usage-and-types.patch
queue-4.19/random-insist-on-random_get_entropy-existing-in-order-to-simplify.patch
queue-4.19/random-group-initialization-wait-functions.patch
queue-4.19/linux-random.h-mark-config_arch_random-functions-__must_check.patch
queue-4.19/random-remove-unused-extract_entropy-reserved-argument.patch
queue-4.19/random-check-for-signal_pending-outside-of-need_resched-check.patch
queue-4.19/random-access-primary_pool-directly-rather-than-through-pointer.patch
queue-4.19/random-fix-sysctl-documentation-nits.patch
queue-4.19/random-remove-unused-tracepoints.patch
queue-4.19/random-only-read-from-dev-random-after-its-pool-has-received-128-bits.patch
queue-4.19/nios2-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-treat-bootloader-trust-toggle-the-same-way-as-cpu-trust-toggle.patch
queue-4.19/random-make-consistent-usage-of-crng_ready.patch
queue-4.19/lib-crypto-blake2s-move-hmac-construction-into-wireguard.patch
queue-4.19/parisc-define-get_cycles-macro-for-arch-override.patch
queue-4.19/x86-tsc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/random-add-grnd_insecure-to-return-best-effort-non-cryptographic-bytes.patch
queue-4.19/crypto-drbg-move-dynamic-reseed_threshold-adjustments-to-__drbg_seed.patch
queue-4.19/random-check-for-signals-after-page-of-pool-writes.patch
queue-4.19/random-make-random_get_entropy-return-an-unsigned-long.patch
queue-4.19/random-check-for-crng_init-0-in-add_device_randomness.patch
queue-4.19/random-remove-unnecessary-unlikely.patch
queue-4.19/random-defer-fast-pool-mixing-to-worker.patch
queue-4.19/random-harmonize-crng-init-done-messages.patch
queue-4.19/crypto-blake2s-include-linux-bug.h-instead-of-asm-bug.h.patch
queue-4.19/random-use-static-branch-for-crng_ready.patch
queue-4.19/random-rather-than-entropy_store-abstraction-use-global.patch
queue-4.19/random-remove-extern-from-functions-in-header.patch
queue-4.19/siphash-use-one-source-of-truth-for-siphash-permutations.patch
queue-4.19/random-group-entropy-collection-functions.patch
queue-4.19/random-de-duplicate-input_pool-constants.patch
queue-4.19/random-mix-build-time-latent-entropy-into-pool-at-init.patch
queue-4.19/random-remove-useless-header-comment.patch
queue-4.19/linux-random.h-use-false-with-bool.patch
queue-4.19/maintainers-co-maintain-random.c.patch
queue-4.19/random-remove-outdated-int_max-6-check-in-urandom_read.patch
queue-4.19/m68k-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-4.19/alpha-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-mix-bootloader-randomness-into-pool.patch
queue-4.19/random-remove-some-dead-code-of-poolinfo.patch
queue-4.19/random-do-not-use-batches-when-crng_ready.patch
queue-4.19/crypto-drbg-always-seeded-with-sp800-90b-compliant-noise-source.patch
queue-4.19/s390-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-do-not-pretend-to-handle-premature-next-security-model.patch
queue-4.19/random-avoid-arch_get_random_seed_long-when-collecting-irq-randomness.patch
queue-4.19/random-use-is_enabled-config_numa-instead-of-ifdefs.patch
queue-4.19/random-avoid-superfluous-call-to-rdrand-in-crng-extraction.patch
queue-4.19/random-use-symbolic-constants-for-crng_init-states.patch
queue-4.19/random-reseed-more-often-immediately-after-booting.patch
queue-4.19/random-ensure-early-rdseed-goes-through-mixer-on-init.patch
queue-4.19/random-deobfuscate-irq-u32-u64-contributions.patch
queue-4.19/random-do-not-use-input-pool-from-hard-irqs.patch
queue-4.19/random-help-compiler-out-with-fast_mix-by-using-simpler-arguments.patch
queue-4.19/revert-random-use-static-branch-for-crng_ready.patch
queue-4.19/random-fix-crash-on-multiple-early-calls-to-add_bootloader_randomness.patch
queue-4.19/random-account-for-arch-randomness-in-bits.patch
queue-4.19/crypto-blake2s-adjust-include-guard-naming.patch
queue-4.19/random-do-not-allow-user-to-keep-crng-key-around-on-stack.patch
queue-4.19/x86-remove-arch_has_random-arch_has_random_seed.patch
queue-4.19/random-remove-ratelimiting-for-in-kernel-unseeded-randomness.patch
queue-4.19/random-remove-unused-irq_flags-argument-from-add_interrupt_randomness.patch
queue-4.19/random-prepend-remaining-pool-constants-with-pool_.patch
queue-4.19/powerpc-define-get_cycles-macro-for-arch-override.patch
queue-4.19/random-remove-unused-output_pool-constants.patch
queue-4.19/mips-use-fallback-for-random_get_entropy-instead-of-just-c0-random.patch
queue-4.19/random-use-hash-function-for-crng_slow_load.patch
queue-4.19/random-fix-typo-in-comments.patch
queue-4.19/random-use-proper-return-types-on-get_random_-int-long-_wait.patch
