From 0b3a2c9968d453d5827e635a6f3d69129f70af66 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Thu, 2 Jan 2014 19:52:20 +0900 Subject: [PATCH] GFS2: Fix unsafe dereference in dump_holder() GLOCK_BUG_ON() might call this function without RCU read lock. Make sure that RCU read lock is held when using task_struct returned from pid_task(). Signed-off-by: Tetsuo Handa Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index c8420f7e4db6..6f7a47c05259 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1655,6 +1655,7 @@ static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh) struct task_struct *gh_owner = NULL; char flags_buf[32]; + rcu_read_lock(); if (gh->gh_owner_pid) gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID); gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n", @@ -1664,6 +1665,7 @@ static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh) gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1, gh_owner ? gh_owner->comm : "(ended)", (void *)gh->gh_ip); + rcu_read_unlock(); return 0; } -- 2.20.1