| Message ID | 20211130141009.6791-4-nstange@suse.de (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | crypto: jitterentropy - bound collection loop | expand |
Am Dienstag, 30. November 2021, 15:10:09 CET schrieb Nicolai Stange: Hi Nicolai, > 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 <nstange@suse.de> Reviewed-by: Stephan Mueller <smueller@chronox.de> Thanks Stephan > --- > crypto/jitterentropy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c > index 24e087c3f526..8f5283f28ed3 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; Ciao Stephan
diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c index 24e087c3f526..8f5283f28ed3 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;
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 <nstange@suse.de> --- crypto/jitterentropy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)