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When a process has been waiting on a condition variable or mutex the

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td_wmesg field in the thread structure points to the description string of
the condition variable or mutex. If the condvar or the mutex had been
initialized from a loadable module that was unloaded in the meantime,
td_wmesg may now point to invalid memory. Retrieving the process table now
may panic the kernel (or access junk). Setting the td_wmesg field to NULL
after unblocking on the condvar/mutex prevents this panic.

PR:		kern/47408
Approved by:	jake (mentor)
This commit is contained in:
Hartmut Brandt 2003-02-27 08:43:27 +00:00
parent 04a2863cfd
commit b89bc9e62b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=111605
2 changed files with 3 additions and 0 deletions
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1
sys/kern/kern_condvar.c
View File

@ -535,6 +535,7 @@ cv_waitq_remove(struct thread *td)
if ((cvp = td->td_wchan) != NULL && td->td_flags & TDF_CVWAITQ) {
TAILQ_REMOVE(&cvp->cv_waitq, td, td_slpq);
td->td_flags &= ~TDF_CVWAITQ;
td->td_wmesg = NULL;
TD_CLR_ON_SLEEPQ(td);
}
}

2
sys/kern/kern_synch.c
View File

@ -330,6 +330,7 @@ endtsleep(arg)
TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq);
TD_CLR_ON_SLEEPQ(td);
td->td_flags |= TDF_TIMEOUT;
td->td_wmesg = NULL;
} else {
td->td_flags |= TDF_TIMOFAIL;
}
@ -374,6 +375,7 @@ unsleep(struct thread *td)
if (TD_ON_SLEEPQ(td)) {
TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq);
TD_CLR_ON_SLEEPQ(td);
td->td_wmesg = NULL;
}
mtx_unlock_spin(&sched_lock);
}