From: Pan Bian <bianpan2016@163.com>
To: Ian Kent <raven@themaw.net>
Cc: autofs@vger.kernel.org, linux-kernel@vger.kernel.org,
Pan Bian <bianpan2016@163.com>
Subject: [PATCH] autofs: drop dentry reference only when it is never used
Date: Mon, 26 Nov 2018 09:58:14 +0800 [thread overview]
Message-ID: <1543197494-15688-1-git-send-email-bianpan2016@163.com> (raw)
The function 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.
Signed-off-by: Pan Bian <bianpan2016@163.com>
---
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 d441244..28d9c2b 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;
}
--
2.7.4
next reply other threads:[~2018-11-26 1:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 1:58 Pan Bian [this message]
2018-11-26 10:36 ` [PATCH] autofs: drop dentry reference only when it is never used Ian Kent
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