scheduler: fix SCHED_DEADLINE upper bound check to reject 2^63 by Rajkaran-122 · Pull Request #2232 · containers/crun

Rajkaran-122 · 2026-09-03T11:08:45Z

Per sched(7), SCHED_DEADLINE parameters must be at least 1024 and less than 2^63. The current code uses greater than max with max = 2^63, which incorrectly accepts values equal to 2^63. Change the check to greater than or equal to max to reject the endpoint as required by the kernel spec.

Update error messages to accurately reflect the valid range using must be greater than or equal to 1024 and less than 2^63 instead of must be between.

Add regression tests for:

Valid upper boundary (2^63 - 1)
Invalid upper boundary (2^63) for runtime, deadline, and period
Valid lower boundary (1024)

Fixes #2190

packit-as-a-service · 2026-09-03T11:13:29Z

Ephemeral COPR build failed. @containers/packit-build please check.

giuseppe · 2026-09-03T14:55:07Z

tests are failing

@eriksjolund PTAL

kolyshkin · 2026-09-03T16:59:31Z

-        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` period (%" PRIu64 ") must be between %" PRIu64 " and %" PRIu64,
+      if (attr->sched_period != 0 && (attr->sched_period < min || attr->sched_period >= max))
+        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` period (%" PRIu64 ") must be >= %" PRIu64 " and < %" PRIu64,
                                attr->sched_period, min, max);


Perhaps it's easier to just change max to

- const uint64_t max = 1ULL << 63; + const uint64_t max = (1ULL << 63) - 1;

?

An advantage of using

const uint64_t max = (1ULL << 63) - 1;

is that the variable max will be set to the maximum allowed value. (The variable name then makes more sense)

eriksjolund · 2026-09-03T17:29:08Z

LGTM

(I just reviewed the changes in src/libcrun/scheduler.c‎)

kolyshkin · 2026-09-04T06:35:03Z

@@ -130,16 +123,16 @@ diagnose_scheduler_failure (libcrun_error_t *err, runtime_spec_schema_config_sch
      /* sched(7) says "under the current implementation, all of the parameter values
       * must be at least 1024 <...> and less than 2^63". */
      const uint64_t min = 1024;
-      const uint64_t max = 1ULL << 63;
+      const uint64_t max = (1ULL << 63) - 1;

      if (attr->sched_runtime < min || attr->sched_runtime > max)
-        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` runtime (%" PRIu64 ") must be between %" PRIu64 " and %" PRIu64,
+        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` runtime (%" PRIu64 ") must be >= %" PRIu64 " and <= %" PRIu64,
                                attr->sched_runtime, min, max);
      if (attr->sched_deadline < min || attr->sched_deadline > max)
-        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` deadline (%" PRIu64 ") must be between %" PRIu64 " and %" PRIu64,
+        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` deadline (%" PRIu64 ") must be >= %" PRIu64 " and <= %" PRIu64,
                                attr->sched_deadline, min, max);
      if (attr->sched_period != 0 && (attr->sched_period < min || attr->sched_period > max))
-        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` period (%" PRIu64 ") must be between %" PRIu64 " and %" PRIu64,
+        return crun_make_error (err, errno, "sched_setattr: `SCHED_DEADLINE` period (%" PRIu64 ") must be >= %" PRIu64 " and <= %" PRIu64,


Can we just keep the old error messages?

@Rajkaran-122 ^^^

kolyshkin

I took a brief look at the test cases -- and it is ridiculous to have 20+ lines of code to check each and every boundary values.

Maybe the new tests does not make any sense?

kolyshkin · 2026-09-09T03:40:13Z

I took a brief look at the test cases -- and it is ridiculous to have 20+ lines of code to check each and every boundary values.

Maybe the new tests does not make any sense?

@Rajkaran-122 ^^^

giuseppe · 2026-09-10T14:41:53Z

please apply the fixup and commit the final clean patch

Per sched(7), SCHED_DEADLINE parameters must be at least 1024 and less than 2^63. The current code uses greater than max with max = 2^63, which incorrectly accepts values equal to 2^63. Change the check to greater than or equal to max to reject the endpoint as required by the kernel spec. Add regression test for the specific bug (2^63 rejection). Fixes containers#2190 Signed-off-by: Rajkaran Yadav <yadavrajkaran854@gmail.com>

Per sched(7), SCHED_DEADLINE parameters must be at least 1024 and less than 2^63. The current code uses greater than max with max = 2^63, which incorrectly accepts values equal to 2^63. Change the check to greater than or equal to max to reject the endpoint as required by the kernel spec. Add regression test for the specific bug (2^63 rejection). Fixes containers#2190 Signed-off-by: Rajkaran Yadav <yadavrajkaran854@gmail.com> Fixup: simplify max to (1ULL << 63) - 1 and restore original error messages. Per review feedback, adjust max to (1ULL << 63) - 1 instead of changing comparisons to >=. Restore original "must be between" error messages.

Rajkaran-122 · 2026-09-10T17:20:09Z

@giuseppe sir PTAL .

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from 271f7b4 to ead13d8 Compare September 3, 2026 11:11

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from ead13d8 to 88a96d9 Compare September 3, 2026 16:01

kolyshkin reviewed Sep 3, 2026

View reviewed changes

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from 88a96d9 to 6d87085 Compare September 3, 2026 17:13

kolyshkin reviewed Sep 4, 2026

View reviewed changes

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from 6d87085 to 11e58bc Compare September 4, 2026 08:29

Rajkaran-122 requested review from eriksjolund and kolyshkin September 4, 2026 09:44

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from 051e55f to 7b5baa0 Compare September 9, 2026 19:13

Rajkaran-122 added 2 commits September 10, 2026 22:12

Rajkaran-122 force-pushed the issue-2190-sched-deadline-range branch from 7b5baa0 to 115c65d Compare September 10, 2026 16:53

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scheduler: fix SCHED_DEADLINE upper bound check to reject 2^63 - #2232

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