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exec:check_unsafe_exec: use while_each_thread() rather than next_thread()

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next_thread() should be avoided, change check_unsafe_exec() to use
while_each_thread().

Nobody except signal->curr_target actually needs next_thread-like code,
and we need to change (fix) this interface.  This particular code is fine,
p == current.  But in general the code like this can loop forever if p
exits and next_thread(t) can't reach the unhashed thread.

This also saves 32 bytes.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-01-23 15:55:49 -08:00 committed by Linus Torvalds
parent 68ce670b6e
commit 83f62a2eac
1 changed files with 2 additions and 1 deletions
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3
fs/exec.c
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@ -1243,10 +1243,11 @@ static int check_unsafe_exec(struct linux_binprm *bprm)
if (current->no_new_privs)
bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
t = p;
n_fs = 1;
spin_lock(&p->fs->lock);
rcu_read_lock();
for (t = next_thread(p); t != p; t = next_thread(t)) {
while_each_thread(p, t) {
if (t->fs == p->fs)
n_fs++;
}