waitid(2): leave copyout of siginfo to syscall itself
have kernel_waitid() collect the information needed for siginfo into a small structure (waitid_info) passed to it; deal with copyout in sys_waitid()/compat_sys_waitid(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>zero-colors
Al Viro
parent
359566faef
commit
67d7ddded3
168
kernel/exit.c
168
kernel/exit.c
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@ -996,12 +996,19 @@ SYSCALL_DEFINE1(exit_group, int, error_code)
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return 0;
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}
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struct waitid_info {
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pid_t pid;
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uid_t uid;
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int status;
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int cause;
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};
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struct wait_opts {
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enum pid_type wo_type;
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int wo_flags;
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struct pid *wo_pid;
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struct siginfo __user *wo_info;
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struct waitid_info *wo_info;
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int wo_stat;
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struct rusage *wo_rusage;
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@ -1053,8 +1060,7 @@ eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
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static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
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pid_t pid, uid_t uid, int why, int status)
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{
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struct siginfo __user *infop;
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int retval = 0;
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struct waitid_info *infop;
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if (wo->wo_rusage)
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getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
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@ -1062,22 +1068,12 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
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put_task_struct(p);
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infop = wo->wo_info;
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if (infop) {
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if (!retval)
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retval = put_user(SIGCHLD, &infop->si_signo);
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if (!retval)
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retval = put_user(0, &infop->si_errno);
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if (!retval)
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retval = put_user((short)why, &infop->si_code);
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if (!retval)
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retval = put_user(pid, &infop->si_pid);
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if (!retval)
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retval = put_user(uid, &infop->si_uid);
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if (!retval)
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retval = put_user(status, &infop->si_status);
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infop->cause = why;
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infop->pid = pid;
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infop->uid = uid;
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infop->status = status;
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}
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if (!retval)
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retval = pid;
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return retval;
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return pid;
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}
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/*
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@ -1088,10 +1084,10 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
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*/
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static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
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{
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int state, retval, status;
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int state, status;
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pid_t pid = task_pid_vnr(p);
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uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
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struct siginfo __user *infop;
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struct waitid_info *infop;
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if (!likely(wo->wo_flags & WEXITED))
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return 0;
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@ -1186,36 +1182,22 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
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if (wo->wo_rusage)
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getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
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retval = 0;
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status = (p->signal->flags & SIGNAL_GROUP_EXIT)
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? p->signal->group_exit_code : p->exit_code;
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wo->wo_stat = status;
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infop = wo->wo_info;
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if (!retval && infop)
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retval = put_user(SIGCHLD, &infop->si_signo);
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if (!retval && infop)
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retval = put_user(0, &infop->si_errno);
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if (!retval && infop) {
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int why;
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if (infop) {
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if ((status & 0x7f) == 0) {
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why = CLD_EXITED;
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status >>= 8;
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infop->cause = CLD_EXITED;
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infop->status = status >> 8;
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} else {
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why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
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status &= 0x7f;
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infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
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infop->status = status & 0x7f;
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}
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retval = put_user((short)why, &infop->si_code);
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if (!retval)
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retval = put_user(status, &infop->si_status);
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infop->pid = pid;
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infop->uid = uid;
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}
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if (!retval && infop)
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retval = put_user(pid, &infop->si_pid);
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if (!retval && infop)
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retval = put_user(uid, &infop->si_uid);
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if (!retval)
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retval = pid;
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if (state == EXIT_TRACE) {
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write_lock_irq(&tasklist_lock);
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@ -1232,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
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if (state == EXIT_DEAD)
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release_task(p);
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return retval;
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return pid;
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}
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static int *task_stopped_code(struct task_struct *p, bool ptrace)
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@ -1268,8 +1250,8 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace)
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static int wait_task_stopped(struct wait_opts *wo,
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int ptrace, struct task_struct *p)
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{
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struct siginfo __user *infop;
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int retval, exit_code, *p_code, why;
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struct waitid_info *infop;
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int exit_code, *p_code, why;
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uid_t uid = 0; /* unneeded, required by compiler */
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pid_t pid;
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@ -1320,28 +1302,19 @@ unlock_sig:
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if (wo->wo_rusage)
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getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
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retval = 0;
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wo->wo_stat = (exit_code << 8) | 0x7f;
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infop = wo->wo_info;
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if (!retval && infop)
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retval = put_user(SIGCHLD, &infop->si_signo);
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if (!retval && infop)
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retval = put_user(0, &infop->si_errno);
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if (!retval && infop)
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retval = put_user((short)why, &infop->si_code);
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if (!retval && infop)
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retval = put_user(exit_code, &infop->si_status);
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if (!retval && infop)
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retval = put_user(pid, &infop->si_pid);
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if (!retval && infop)
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retval = put_user(uid, &infop->si_uid);
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if (!retval)
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retval = pid;
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if (infop) {
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infop->cause = why;
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infop->status = exit_code;
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infop->pid = pid;
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infop->uid = uid;
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}
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put_task_struct(p);
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BUG_ON(!retval);
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return retval;
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BUG_ON(!pid);
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return pid;
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}
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/*
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@ -1618,7 +1591,7 @@ end:
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return retval;
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}
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static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop,
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static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
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int options, struct rusage *ru)
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{
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struct wait_opts wo;
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@ -1660,27 +1633,8 @@ static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop,
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wo.wo_rusage = ru;
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ret = do_wait(&wo);
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if (ret > 0) {
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if (ret > 0)
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ret = 0;
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} else if (infop) {
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/*
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* For a WNOHANG return, clear out all the fields
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* we would set so the user can easily tell the
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* difference.
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*/
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if (!ret)
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ret = put_user(0, &infop->si_signo);
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if (!ret)
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ret = put_user(0, &infop->si_errno);
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if (!ret)
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ret = put_user(0, &infop->si_code);
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if (!ret)
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ret = put_user(0, &infop->si_pid);
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if (!ret)
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ret = put_user(0, &infop->si_uid);
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if (!ret)
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ret = put_user(0, &infop->si_status);
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}
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put_pid(pid);
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return ret;
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@ -1690,12 +1644,24 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
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infop, int, options, struct rusage __user *, ru)
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{
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struct rusage r;
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long err = kernel_waitid(which, upid, infop, options, ru ? &r : NULL);
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struct waitid_info info = {.status = 0};
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long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
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if (!err) {
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if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
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return -EFAULT;
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}
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if (!infop)
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return err;
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if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) ||
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put_user(0, &infop->si_errno) ||
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put_user((short)info.cause, &infop->si_code) ||
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put_user(info.pid, &infop->si_pid) ||
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put_user(info.uid, &infop->si_uid) ||
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put_user(info.status, &infop->si_status))
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err = -EFAULT;
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return err;
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}
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@ -1785,33 +1751,27 @@ COMPAT_SYSCALL_DEFINE5(waitid,
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struct compat_siginfo __user *, infop, int, options,
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struct compat_rusage __user *, uru)
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{
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siginfo_t info;
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struct rusage ru;
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long ret;
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mm_segment_t old_fs = get_fs();
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struct waitid_info info = {.status = 0};
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long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
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memset(&info, 0, sizeof(info));
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set_fs(KERNEL_DS);
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ret = kernel_waitid(which, pid, (siginfo_t __user *)&info, options,
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uru ? &ru : NULL);
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set_fs(old_fs);
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if ((ret < 0) || (info.si_signo == 0))
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return ret;
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if (uru) {
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/* sys_waitid() overwrites everything in ru */
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if (!err && uru) {
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/* kernel_waitid() overwrites everything in ru */
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if (COMPAT_USE_64BIT_TIME)
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ret = copy_to_user(uru, &ru, sizeof(ru));
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err = copy_to_user(uru, &ru, sizeof(ru));
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else
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ret = put_compat_rusage(&ru, uru);
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if (ret)
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err = put_compat_rusage(&ru, uru);
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if (err)
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return -EFAULT;
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}
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BUG_ON(info.si_code & __SI_MASK);
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info.si_code |= __SI_CHLD;
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return copy_siginfo_to_user32(infop, &info);
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if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) ||
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put_user(0, &infop->si_errno) ||
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put_user((short)info.cause, &infop->si_code) ||
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put_user(info.pid, &infop->si_pid) ||
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put_user(info.uid, &infop->si_uid) ||
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put_user(info.status, &infop->si_status))
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err = -EFAULT;
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return err;
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}
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#endif
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