| From 8b8f0489ab3e9852bc8abb1300253aaa6a9f4b72 Mon Sep 17 00:00:00 2001 |
| From: Pan Bian <bianpan2016@163.com> |
| Date: Fri, 1 Feb 2019 14:21:26 -0800 |
| Subject: autofs: drop dentry reference only when it is never used |
| |
| [ Upstream commit 63ce5f552beb9bdb41546b3a26c4374758b21815 ] |
| |
| autofs_expire_run() calls dput(dentry) to drop the reference count of |
| dentry. However, dentry is read via autofs_dentry_ino(dentry) after |
| that. This may result in a use-free-bug. The patch drops the reference |
| count of dentry only when it is never used. |
| |
| Link: http://lkml.kernel.org/r/154725122396.11260.16053424107144453867.stgit@pluto-themaw-net |
| Signed-off-by: Pan Bian <bianpan2016@163.com> |
| Signed-off-by: Ian Kent <raven@themaw.net> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| fs/autofs/expire.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c |
| index d441244b79df..28d9c2b1b3bb 100644 |
| --- a/fs/autofs/expire.c |
| +++ b/fs/autofs/expire.c |
| @@ -596,7 +596,6 @@ int autofs_expire_run(struct super_block *sb, |
| pkt.len = dentry->d_name.len; |
| memcpy(pkt.name, dentry->d_name.name, pkt.len); |
| pkt.name[pkt.len] = '\0'; |
| - dput(dentry); |
| |
| if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire))) |
| ret = -EFAULT; |
| @@ -609,6 +608,8 @@ int autofs_expire_run(struct super_block *sb, |
| complete_all(&ino->expire_complete); |
| spin_unlock(&sbi->fs_lock); |
| |
| + dput(dentry); |
| + |
| return ret; |
| } |
| |
| -- |
| 2.19.1 |
| |
