Rich Felker
2b2c8aafce
kernel commit 4693916846269d633a3664586650dbfac2c5562f (first included in release v4.14) silently fixed a bug whereby the reserved space (which was later used for high bits of time) in IPC_STAT structures was left untouched rather than zeroed. this means that a caller that wants to read the high bits needs to pre-zero the memory. since it's not clear that these operations are permitted to modify the destination buffer on failure, use a temp buffer and copy back to the caller's buffer on success.
70 lines
1.4 KiB
C
70 lines
1.4 KiB
C
#include <sys/sem.h>
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#include <stdarg.h>
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#include <endian.h>
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#include "syscall.h"
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#include "ipc.h"
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#if __BYTE_ORDER != __BIG_ENDIAN
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#undef SYSCALL_IPC_BROKEN_MODE
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#endif
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union semun {
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int val;
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struct semid_ds *buf;
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unsigned short *array;
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};
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int semctl(int id, int num, int cmd, ...)
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{
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union semun arg = {0};
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va_list ap;
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switch (cmd & ~IPC_TIME64) {
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case SETVAL: case GETALL: case SETALL: case IPC_SET:
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case IPC_INFO: case SEM_INFO:
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case IPC_STAT & ~IPC_TIME64:
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case SEM_STAT & ~IPC_TIME64:
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case SEM_STAT_ANY & ~IPC_TIME64:
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va_start(ap, cmd);
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arg = va_arg(ap, union semun);
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va_end(ap);
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}
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#if IPC_TIME64
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struct semid_ds out, *orig;
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if (cmd&IPC_TIME64) {
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out = (struct semid_ds){0};
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orig = arg.buf;
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arg.buf = &out;
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}
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#endif
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#ifdef SYSCALL_IPC_BROKEN_MODE
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struct semid_ds tmp;
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if (cmd == IPC_SET) {
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tmp = *arg.buf;
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tmp.sem_perm.mode *= 0x10000U;
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arg.buf = &tmp;
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}
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#endif
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#ifndef SYS_ipc
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int r = __syscall(SYS_semctl, id, num, IPC_CMD(cmd), arg.buf);
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#else
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int r = __syscall(SYS_ipc, IPCOP_semctl, id, num, IPC_CMD(cmd), &arg.buf);
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#endif
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#ifdef SYSCALL_IPC_BROKEN_MODE
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if (r >= 0) switch (cmd | IPC_TIME64) {
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case IPC_STAT:
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case SEM_STAT:
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case SEM_STAT_ANY:
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arg.buf->sem_perm.mode >>= 16;
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}
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#endif
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#if IPC_TIME64
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if (r >= 0 && (cmd&IPC_TIME64)) {
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arg.buf = orig;
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*arg.buf = out;
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IPC_HILO(arg.buf, sem_otime);
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IPC_HILO(arg.buf, sem_ctime);
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}
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#endif
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return __syscall_ret(r);
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}
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