[PATCH 50/80] tty: Fix abusers of current->sighand->tty

Alan Cox
2008-10-13T09:52:09Z

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>
---

kernel/acct.c | 2 +-
kernel/auditsc.c | 9 ++++-----
2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/acct.c b/kernel/acct.c
index dd68b90..f6006a6 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -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)));
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 59cedfb..cf5bc2f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -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) {