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https://github.com/edk2-porting/linux-next.git
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380af1b33b
The attached patch: - reverses the locking order of ulp->lock and sem_lock: Previously, it was first ulp->lock, then inside sem_lock. Now it's the other way around. - converts the undo structure to rcu. Benefits: - With the old locking order, IPC_RMID could not kfree the undo structures. The stale entries remained in the linked lists and were released later. - The patch fixes a a race in semtimedop(): if both IPC_RMID and a semget() that recreates exactly the same id happen between find_alloc_undo() and sem_lock, then semtimedop() would access already kfree'd memory. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Reviewed-by: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
160 lines
4.9 KiB
C
160 lines
4.9 KiB
C
#ifndef _LINUX_SEM_H
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#define _LINUX_SEM_H
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#include <linux/ipc.h>
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/* semop flags */
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#define SEM_UNDO 0x1000 /* undo the operation on exit */
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/* semctl Command Definitions. */
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#define GETPID 11 /* get sempid */
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#define GETVAL 12 /* get semval */
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#define GETALL 13 /* get all semval's */
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#define GETNCNT 14 /* get semncnt */
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#define GETZCNT 15 /* get semzcnt */
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#define SETVAL 16 /* set semval */
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#define SETALL 17 /* set all semval's */
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/* ipcs ctl cmds */
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#define SEM_STAT 18
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#define SEM_INFO 19
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/* Obsolete, used only for backwards compatibility and libc5 compiles */
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struct semid_ds {
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struct ipc_perm sem_perm; /* permissions .. see ipc.h */
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__kernel_time_t sem_otime; /* last semop time */
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__kernel_time_t sem_ctime; /* last change time */
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct sem_queue *sem_pending; /* pending operations to be processed */
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struct sem_queue **sem_pending_last; /* last pending operation */
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struct sem_undo *undo; /* undo requests on this array */
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unsigned short sem_nsems; /* no. of semaphores in array */
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};
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/* Include the definition of semid64_ds */
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#include <asm/sembuf.h>
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/* semop system calls takes an array of these. */
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struct sembuf {
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unsigned short sem_num; /* semaphore index in array */
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short sem_op; /* semaphore operation */
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short sem_flg; /* operation flags */
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};
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/* arg for semctl system calls. */
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds __user *buf; /* buffer for IPC_STAT & IPC_SET */
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unsigned short __user *array; /* array for GETALL & SETALL */
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struct seminfo __user *__buf; /* buffer for IPC_INFO */
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void __user *__pad;
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};
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struct seminfo {
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int semmap;
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int semmni;
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int semmns;
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int semmnu;
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int semmsl;
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int semopm;
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int semume;
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int semusz;
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int semvmx;
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int semaem;
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};
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#define SEMMNI 128 /* <= IPCMNI max # of semaphore identifiers */
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#define SEMMSL 250 /* <= 8 000 max num of semaphores per id */
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#define SEMMNS (SEMMNI*SEMMSL) /* <= INT_MAX max # of semaphores in system */
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#define SEMOPM 32 /* <= 1 000 max num of ops per semop call */
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#define SEMVMX 32767 /* <= 32767 semaphore maximum value */
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#define SEMAEM SEMVMX /* adjust on exit max value */
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/* unused */
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#define SEMUME SEMOPM /* max num of undo entries per process */
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#define SEMMNU SEMMNS /* num of undo structures system wide */
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#define SEMMAP SEMMNS /* # of entries in semaphore map */
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#define SEMUSZ 20 /* sizeof struct sem_undo */
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#ifdef __KERNEL__
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#include <asm/atomic.h>
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#include <linux/rcupdate.h>
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struct task_struct;
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/* One semaphore structure for each semaphore in the system. */
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struct sem {
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int semval; /* current value */
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int sempid; /* pid of last operation */
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};
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/* One sem_array data structure for each set of semaphores in the system. */
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struct sem_array {
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struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */
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time_t sem_otime; /* last semop time */
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time_t sem_ctime; /* last change time */
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct list_head sem_pending; /* pending operations to be processed */
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struct list_head list_id; /* undo requests on this array */
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unsigned long sem_nsems; /* no. of semaphores in array */
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};
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/* One queue for each sleeping process in the system. */
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struct sem_queue {
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struct list_head list; /* queue of pending operations */
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struct task_struct *sleeper; /* this process */
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struct sem_undo *undo; /* undo structure */
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int pid; /* process id of requesting process */
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int status; /* completion status of operation */
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struct sembuf *sops; /* array of pending operations */
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int nsops; /* number of operations */
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int alter; /* does the operation alter the array? */
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};
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/* Each task has a list of undo requests. They are executed automatically
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* when the process exits.
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*/
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struct sem_undo {
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struct list_head list_proc; /* per-process list: all undos from one process. */
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/* rcu protected */
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struct rcu_head rcu; /* rcu struct for sem_undo() */
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struct sem_undo_list *ulp; /* sem_undo_list for the process */
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struct list_head list_id; /* per semaphore array list: all undos for one array */
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int semid; /* semaphore set identifier */
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short * semadj; /* array of adjustments, one per semaphore */
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};
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/* sem_undo_list controls shared access to the list of sem_undo structures
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* that may be shared among all a CLONE_SYSVSEM task group.
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*/
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struct sem_undo_list {
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atomic_t refcnt;
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spinlock_t lock;
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struct list_head list_proc;
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};
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struct sysv_sem {
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struct sem_undo_list *undo_list;
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};
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#ifdef CONFIG_SYSVIPC
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extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
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extern void exit_sem(struct task_struct *tsk);
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#else
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static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
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{
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return 0;
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}
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static inline void exit_sem(struct task_struct *tsk)
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{
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return;
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}
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#endif
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#endif /* __KERNEL__ */
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#endif /* _LINUX_SEM_H */
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