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-rw-r--r--lib/Kconfig.debug28
-rw-r--r--lib/rhashtable.c2
2 files changed, 29 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 789c6e9e5e01..98fe715522e8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1223,6 +1223,34 @@ config STACKTRACE
It is also used by various kernel debugging features that require
stack trace generation.
+config WARN_ALL_UNSEEDED_RANDOM
+ bool "Warn for all uses of unseeded randomness"
+ default n
+ help
+ Some parts of the kernel contain bugs relating to their use of
+ cryptographically secure random numbers before it's actually possible
+ to generate those numbers securely. This setting ensures that these
+ flaws don't go unnoticed, by enabling a message, should this ever
+ occur. This will allow people with obscure setups to know when things
+ are going wrong, so that they might contact developers about fixing
+ it.
+
+ Unfortunately, on some models of some architectures getting
+ a fully seeded CRNG is extremely difficult, and so this can
+ result in dmesg getting spammed for a surprisingly long
+ time. This is really bad from a security perspective, and
+ so architecture maintainers really need to do what they can
+ to get the CRNG seeded sooner after the system is booted.
+ However, since users can not do anything actionble to
+ address this, by default the kernel will issue only a single
+ warning for the first use of unseeded randomness.
+
+ Say Y here if you want to receive warnings for all uses of
+ unseeded randomness. This will be of use primarily for
+ those developers interersted in improving the security of
+ Linux kernels running on their architecture (or
+ subarchitecture).
+
config DEBUG_KOBJECT
bool "kobject debugging"
depends on DEBUG_KERNEL
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 42466c167257..707ca5d677c6 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -234,7 +234,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
INIT_LIST_HEAD(&tbl->walkers);
- get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
+ tbl->hash_rnd = get_random_u32();
for (i = 0; i < nbuckets; i++)
INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);