CVE-2024-56583

In the Linux kernel, the following vulnerability has been resolved:

sched/deadline: Fix warning in migrate_enable for boosted tasks

When running the following command:

while true; do stress-ng --cyclic 30 --timeout 30s --minimize --quiet done

a warning is eventually triggered:

WARNING: CPU: 43 PID: 2848 at kernel/sched/deadline.c:794 setupnewdlentity+0x13e/0x180 ... Call Trace: <TASK> ? showtraceloglvl+0x1c4/0x2df ? enqueuedlentity+0x631/0x6e0 ? setupnewdl_entity+0x13e/0x180 ? __warn+0x7e/0xd0 ? reportbug+0x11a/0x1a0 ? handlebug+0x3c/0x70 ? excinvalidop+0x14/0x70 ? asmexcinvalidop+0x16/0x20 enqueuedlentity+0x631/0x6e0 enqueuetask_dl+0x7d/0x120 __dosetcpus_allowed+0xe3/0x280 __setcpusallowedptrlocked+0x140/0x1d0 __setcpusallowed_ptr+0x54/0xa0 migrateenable+0x7e/0x150 rtspinunlock+0x1c/0x90 groupsendsiginfo+0xf7/0x1a0 ? killpidinfo+0x1f/0x1d0 killpidinfo+0x78/0x1d0 killprocinfo+0x5b/0x110 __x64syskill+0x93/0xc0 dosyscall64+0x5c/0xf0 entrySYSCALL64afterhwframe+0x6e/0x76 RIP: 0033:0x7f0dab31f92b

This warning occurs because setcpusallowed dequeues and enqueues tasks with the ENQUEUERESTORE flag set. If the task is boosted, the warning is triggered. A boosted task already had its parameters set by rtmutexsetprio, and a new call to setupnewdlentity is unnecessary, hence the WARN_ON call.

Check if we are requeueing a boosted task and avoid calling setupnewdl_entity if that's the case.