tty: Fix abusers of current->sighand->tty
Alan Cox [Mon, 13 Oct 2008 09:40:53 +0000 (10:40 +0100)]
Various people outside the tty layer still stick their noses in behind the
scenes. We need to make sure they also obey the locking and referencing rules.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/acct.c
kernel/auditsc.c

index dd68b90..f6006a6 100644 (file)
@@ -548,7 +548,7 @@ static void do_acct_process(struct bsd_acct_struct *acct,
 #endif
 
        spin_lock_irq(&current->sighand->siglock);
-       tty = current->signal->tty;
+       tty = current->signal->tty;     /* Safe as we hold the siglock */
        ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
        ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
        ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
index 59cedfb..cf5bc2f 100644 (file)
@@ -246,8 +246,8 @@ static int audit_match_perm(struct audit_context *ctx, int mask)
        unsigned n;
        if (unlikely(!ctx))
                return 0;
-
        n = ctx->major;
+
        switch (audit_classify_syscall(ctx->arch, n)) {
        case 0: /* native */
                if ((mask & AUDIT_PERM_WRITE) &&
@@ -1204,13 +1204,13 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
                                 (context->return_valid==AUDITSC_SUCCESS)?"yes":"no",
                                 context->return_code);
 
-       mutex_lock(&tty_mutex);
-       read_lock(&tasklist_lock);
+       spin_lock_irq(&tsk->sighand->siglock);
        if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
                tty = tsk->signal->tty->name;
        else
                tty = "(none)";
-       read_unlock(&tasklist_lock);
+       spin_unlock_irq(&tsk->sighand->siglock);
+
        audit_log_format(ab,
                  " a0=%lx a1=%lx a2=%lx a3=%lx items=%d"
                  " ppid=%d pid=%d auid=%u uid=%u gid=%u"
@@ -1230,7 +1230,6 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
                  context->egid, context->sgid, context->fsgid, tty,
                  tsk->sessionid);
 
-       mutex_unlock(&tty_mutex);
 
        audit_log_task_info(ab, tsk);
        if (context->filterkey) {