Messages in this thread Patch in this message | | | Subject | [PATCH] GFS2: Fix unsafe dereference in dump_holder() | From | Tetsuo Handa <> | Date | Tue, 24 Dec 2013 20:51:43 +0900 |
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>From efee681e4ca6152d9549a50e93ca932b00f03014 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Date: Tue, 24 Dec 2013 18:04:43 +0900 Subject: [PATCH] GFS2: Fix unsafe dereference in dump_holder()
Since we are not in RCU nor tasklist_lock held, we need to grab a reference on the returned task_struct. Use get_pid_task()/get_task_comm() to safely read the target task's comm name.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- fs/gfs2/glock.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index c8420f7..7bda965 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1654,15 +1654,22 @@ static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh) { struct task_struct *gh_owner = NULL; char flags_buf[32]; + char name[TASK_COMM_LEN]; if (gh->gh_owner_pid) - gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID); + gh_owner = get_pid_task(gh->gh_owner_pid, PIDTYPE_PID); + if (gh_owner) { + get_task_comm(name, gh_owner); + put_task_struct(gh_owner); + } else { + strlcpy(name, "(ended)", sizeof(name)); + } gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n", state2str(gh->gh_state), hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags), gh->gh_error, gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1, - gh_owner ? gh_owner->comm : "(ended)", + name, (void *)gh->gh_ip); return 0; } -- 1.7.1
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