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Lock the semaphore identifier lock during semaphore initialization to

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guarantee atomicity of the operation for other semaphore consumers.
In particular, this should guard against access to the semaphore with
not done or partially done MAC label assignment.

Reviewed by:	rwatson
MFC after:	1 month
This commit is contained in:
Konstantin Belousov 2009-01-15 12:15:46 +00:00
parent 892f21a681
commit 137cf3b682
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=187298
1 changed files with 4 additions and 0 deletions
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4
sys/kern/sysv_sem.c
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@ -914,6 +914,9 @@ semget(struct thread *td, struct semget_args *uap)
goto done2;
}
DPRINTF(("semid %d is available\n", semid));
mtx_lock(&sema_mtx[semid]);
KASSERT((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0,
("Lost semaphore %d", semid));
sema[semid].u.sem_perm.key = key;
sema[semid].u.sem_perm.cuid = cred->cr_uid;
sema[semid].u.sem_perm.uid = cred->cr_uid;
@ -932,6 +935,7 @@ semget(struct thread *td, struct semget_args *uap)
#ifdef MAC
mac_sysvsem_create(cred, &sema[semid]);
#endif
mtx_unlock(&sema_mtx[semid]);
DPRINTF(("sembase = %p, next = %p\n",
sema[semid].u.sem_base, &sem[semtot]));
} else {