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authorPan Bian <bianpan2016@163.com>2019-02-02 01:21:26 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-02-02 02:46:24 +0300
commit63ce5f552beb9bdb41546b3a26c4374758b21815 (patch)
tree318f69dfe1f4e61e6f5fc4d5c634389f1167289e
parentc27d82f52f75fc9d8d9d40d120d2a96fdeeada5e (diff)
downloadlinux-63ce5f552beb9bdb41546b3a26c4374758b21815.tar.xz
autofs: drop dentry reference only when it is never used
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>
-rw-r--r--fs/autofs/expire.c3
1 files changed, 2 insertions, 1 deletions
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;
}