random: quiet urandom warning ratelimit suppression message

commit a52a45f77759d558cdf47e6f05ac871635a9ff37 upstream.

random.c ratelimits how much it warns about uninitialized urandom reads
using __ratelimit(). When the RNG is finally initialized, it prints the
number of missed messages due to ratelimiting.

It has been this way since that functionality was introduced back in
2018. Recently, 13cd7980484c ("random: remove ratelimiting for in-kernel
unseeded randomness") put a bit more stress on the urandom ratelimiting,
which teased out a bug in the implementation.

Specifically, when under pressure, __ratelimit() will print its own
message and reset the count back to 0, making the final message at the
end less useful. Secondly, it does so as a pr_warn(), which apparently
is undesirable for people's CI.

Fortunately, __ratelimit() has the RATELIMIT_MSG_ON_RELEASE flag exactly
for this purpose, so we set the flag.

Fixes: a0596dd97db5 ("random: rate limit unseeded randomness warnings")
Cc: stable@vger.kernel.org
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: Ron Economos <re@w6rz.net>
Tested-by: Ron Economos <re@w6rz.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index ca5212fbe97f4357dc24b1552be8e027ef1f9dcc..b86bee9284fa193dced6b1ff2f7be66a88994638 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -88,7 +88,7 @@ static RAW_NOTIFIER_HEAD(random_ready_chain);
 
 /* Control how we warn userspace. */
 static struct ratelimit_state urandom_warning =
-       RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
+       RATELIMIT_STATE_INIT_FLAGS("urandom_warning", HZ, 3, RATELIMIT_MSG_ON_RELEASE);
 static int ratelimit_disable __read_mostly =
        IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM);
 module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);

diff --git a/include/linux/ratelimit.h b/include/linux/ratelimit.h
index 8ddf79e9207a9db19a91fd09081f8df3c18eea22..1df12e8dde6f67676c7090843643e60f2e40837a 100644 (file)
--- a/include/linux/ratelimit.h
+++ b/include/linux/ratelimit.h
@@ -23,12 +23,16 @@ struct ratelimit_state {
        unsigned long   flags;
 };
 
-#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) {                \
-               .lock           = __RAW_SPIN_LOCK_UNLOCKED(name.lock),  \
-               .interval       = interval_init,                        \
-               .burst          = burst_init,                           \
+#define RATELIMIT_STATE_INIT_FLAGS(name, interval_init, burst_init, flags_init) { \
+               .lock           = __RAW_SPIN_LOCK_UNLOCKED(name.lock),            \
+               .interval       = interval_init,                                  \
+               .burst          = burst_init,                                     \
+               .flags          = flags_init,                                     \
        }
 
+#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) \
+       RATELIMIT_STATE_INIT_FLAGS(name, interval_init, burst_init, 0)
+
 #define RATELIMIT_STATE_INIT_DISABLED                                  \
        RATELIMIT_STATE_INIT(ratelimit_state, 0, DEFAULT_RATELIMIT_BURST)