The patch titled
pids: sys_getsid: fix unsafe *pid usage, fix possible 0 instead of -ESRCH
has been added to the -mm tree. Its filename is
pids-sys_getsid-fix-unsafe-pid-usage-fix-possible-0-instead-of-esrch.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: pids: sys_getsid: fix unsafe *pid usage, fix possible 0 instead of -ESRCH
From: Oleg Nesterov <oleg@xxxxxxxxxx>
1. sys_getsid() needs rcu_read_lock() to derive the session _nr, even if
the task is current, otherwise we can race with another thread which
does sys_setsid().
2. The task can exit between find_task_by_vpid() and task_session_vnr(),
in that unlikely case sys_getsid() returns 0 instead of -ESRCH.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)
diff -puN kernel/sys.c~pids-sys_getsid-fix-unsafe-pid-usage-fix-possible-0-instead-of-esrch kernel/sys.c
--- a/kernel/sys.c~pids-sys_getsid-fix-unsafe-pid-usage-fix-possible-0-instead-of-esrch
+++ a/kernel/sys.c
@@ -1016,23 +1016,30 @@ asmlinkage long sys_getpgrp(void)
asmlinkage long sys_getsid(pid_t pid)
{
+ struct task_struct *p;
+ struct pid *sid;
+ int retval;
+
+ rcu_read_lock();
if (!pid)
- return task_session_vnr(current);
+ sid = task_session(current);
else {
- int retval;
- struct task_struct *p;
-
- rcu_read_lock();
- p = find_task_by_vpid(pid);
retval = -ESRCH;
- if (p) {
- retval = security_task_getsid(p);
- if (!retval)
- retval = task_session_vnr(p);
- }
- rcu_read_unlock();
- return retval;
+ p = find_task_by_vpid(pid);
+ if (!p)
+ goto out;
+ sid = task_session(p);
+ if (!sid)
+ goto out;
+
+ retval = security_task_getsid(p);
+ if (retval)
+ goto out;
}
+ retval = pid_vnr(sid);
+out:
+ rcu_read_unlock();
+ return retval;
}
asmlinkage long sys_setsid(void)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
bsd_acct-plain-current-real_parent-access-is-not-always-safe.patch
bsd_acct-using-task_struct-tgid-is-not-right-in-pid-namespaces.patch
x86-handle_vm86_trap-cleanup.patch
git-hrt.patch
mmap_region-cleanup-the-final-vma_merge-related-code.patch
kthread-call-wake_up_process-without-the-lock-being-held.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-do_signal_stop-use-signal_group_exit.patch
signals-do_group_exit-use-signal_group_exit-more-consistently.patch
lock_task_sighand-add-rcu-lock-unlock.patch
k_getrusage-dont-take-rcu_read_lock.patch
do_task_stat-dont-take-rcu_read_lock.patch
signals-consolidate-checks-for-whether-or-not-to-ignore-a-signal.patch
signals-clean-dequeue_signal-from-excess-checks-and-assignments.patch
signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch
signals-cleanup-security_task_kill-usage-implementation.patch
signals-re-assign-cld_continued-notification-from-the-sender-to-reciever.patch
kill_pid_info-dont-take-now-unneeded-tasklist_lock.patch
handle_stop_signal-unify-partial-full-stop-handling.patch
handle_stop_signal-use-the-cached-p-signal-value.patch
get_signal_to_deliver-use-the-cached-signal-sighand-values.patch
signals-send_sigqueue-dont-take-rcu-lock.patch
signals-send_sigqueue-dont-forget-about-handle_stop_signal.patch
signals-__group_complete_signal-cache-the-value-of-p-signal.patch
signals-send_group_sigqueue-dont-take-tasklist_lock.patch
signals-move-handle_stop_signal-into-send_signal.patch
signals-do_tkill-dont-use-tasklist_lock.patch
signals-do_tkill-dont-use-tasklist_lock-comment.patch
signals-send_sig_info-dont-take-tasklist_lock.patch
signals-microoptimize-the-usage-of-curr_target.patch
signals-move-the-definition-of-__group_complete_signal-up.patch
signals-change-send_signal-do_send_sigqueue-to-take-boolean-group-parameter.patch
signals-use-__group_complete_signal-for-the-specific-signals-too.patch
signals-fold-complete_signal-into-send_signal-do_send_sigqueue.patch
signals-unify-send_sigqueue-send_group_sigqueue-completely.patch
signals-join-send_sigqueue-with-send_group_sigqueue.patch
signals-handle_stop_signal-dont-worry-about-sigkill.patch
signals-cleanup-the-usage-of-print_fatal_signal.patch
signals-fold-sig_ignored-into-handle_stop_signal.patch
signals-fold-sig_ignored-into-handle_stop_signal-comment.patch
signals-document-cld_continued-notification-mechanics.patch
signals-document-cld_continued-notification-mechanics-more.patch
signals-send_signal-be-paranoid-about-signalfd_notify.patch
signals-check_kill_permission-check-session-under-tasklist_lock.patch
signals-check_kill_permission-remove-tasklist_lock.patch
signals-fix-sbin-init-protection-from-unwanted-signals.patch
signals-de_thread-simplify-the-child_reaper-switching.patch
signals-allow-the-kernel-to-actually-kill-sbin-init.patch
ptrace-introduce-task_detached-helper.patch
reparent_thread-use-same_thread_group.patch
document-de_thread-with-exit_notify-connection.patch
ptrace-introduce-ptrace_reparented-helper.patch
ptrace-__ptrace_unlink-use-the-ptrace_reparented-helper.patch
ptrace-ptrace_attach-use-send_sig_info-instead-force_sig_specific.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies-fix.patch
cleanup_workqueue_thread-remove-the-unneeded-cpu-parameter.patch
simplify-cpu_hotplug_begin-put_online_cpus.patch
redo-locking-of-tty-pgrp.patch
resume-tty-on-susp-and-fix-crnl-order-in-n_tty-line-discipline.patch
tty_io-fix-remaining-pid-struct-locking.patch
tty_io-fix-remaining-pid-struct-locking-small-cleanup.patch
procfs-task-exe-symlink.patch
procfs-task-exe-symlink-fix.patch
procfs-task-exe-symlink-fix-2.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
pids-de_thread-dont-clear-session-pgrp-pids-for-the-old-leader.patch
pids-introduce-change_pid-helper.patch
pids-sys_setpgid-use-change_pid-helper.patch
pids-__set_special_pids-use-change_pid-helper.patch
pids-sys_getsid-fix-unsafe-pid-usage-fix-possible-0-instead-of-esrch.patch
pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
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