kernel: ipc/sem.c: reading uninitialized stack memory

The copysemidtouser function in ipc/sem.c in the Linux kernel before 2.6.36 does not initialize a certain structure, which allows local users to obtain potentially sensitive information from kernel stack memory via a 1 IPCINFO, 2 SEMINFO, 3 IPCSTAT, or 4 SEMSTAT command in a semctl system call...