From fca178c0c6e8d52a1875be36b070f30884ebfae9 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 28 Oct 2006 10:38:49 -0700 Subject: [PATCH] [PATCH] fill_tgid: fix task_struct leak and possible oops 1. fill_tgid() forgets to do put_task_struct(first). 2. release_task(first) can happen after fill_tgid() drops tasklist_lock, it is unsafe to dereference first->signal. This is a temporary fix, imho the locking should be reworked. Signed-off-by: Oleg Nesterov Cc: Shailabh Nagar Cc: Balbir Singh Cc: Jay Lan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/taskstats.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/kernel/taskstats.c b/kernel/taskstats.c index 5d6a8c54ee..9aeee511a4 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -237,14 +237,17 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk, } else get_task_struct(first); - /* Start with stats from dead tasks */ - spin_lock_irqsave(&first->signal->stats_lock, flags); - if (first->signal->stats) - memcpy(stats, first->signal->stats, sizeof(*stats)); - spin_unlock_irqrestore(&first->signal->stats_lock, flags); tsk = first; read_lock(&tasklist_lock); + /* Start with stats from dead tasks */ + if (first->signal) { + spin_lock_irqsave(&first->signal->stats_lock, flags); + if (first->signal->stats) + memcpy(stats, first->signal->stats, sizeof(*stats)); + spin_unlock_irqrestore(&first->signal->stats_lock, flags); + } + do { if (tsk->exit_state == EXIT_ZOMBIE && thread_group_leader(tsk)) continue; @@ -264,7 +267,7 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk, * Accounting subsytems can also add calls here to modify * fields of taskstats. */ - + put_task_struct(first); return 0; } -- 2.39.5