From 710ce4b88f9a93a6b2c2267e8f27ba65af3cb6ac Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Tue, 30 Nov 2021 15:10:09 +0100 Subject: [PATCH] crypto: jitter - quit sample collection loop upon RCT failure The jitterentropy collection loop in jent_gen_entropy() can in principle run indefinitely without making any progress if it only receives stuck measurements as determined by jent_stuck(). After 31 consecutive stuck samples, the Repetition Count Test (RCT) would fail anyway and the jitterentropy RNG instances moved into ->health_failure == 1 state. jent_gen_entropy()'s caller, jent_read_entropy() would then check for this ->health_failure condition and return an error if found set. It follows that there's absolutely no point in continuing the collection loop in jent_gen_entropy() once the RCT has failed. Make the jitterentropy collection loop more robust by terminating it upon jent_health_failure() so that it won't continue to run indefinitely without making any progress. Signed-off-by: Nicolai Stange Reviewed-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/jitterentropy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c index 24e087c..8f5283f 100644 --- a/crypto/jitterentropy.c +++ b/crypto/jitterentropy.c @@ -547,7 +547,7 @@ static void jent_gen_entropy(struct rand_data *ec) /* priming of the ->prev_time value */ jent_measure_jitter(ec); - while (1) { + while (!jent_health_failure(ec)) { /* If a stuck measurement is received, repeat measurement */ if (jent_measure_jitter(ec)) continue; -- 2.7.4