Commit 63ce5f55 authored by Pan Bian's avatar Pan Bian Committed by Linus Torvalds

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-netSigned-off-by: default avatarPan Bian <bianpan2016@163.com>
Signed-off-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c27d82f5
...@@ -596,7 +596,6 @@ int autofs_expire_run(struct super_block *sb, ...@@ -596,7 +596,6 @@ int autofs_expire_run(struct super_block *sb,
pkt.len = dentry->d_name.len; pkt.len = dentry->d_name.len;
memcpy(pkt.name, dentry->d_name.name, pkt.len); memcpy(pkt.name, dentry->d_name.name, pkt.len);
pkt.name[pkt.len] = '\0'; pkt.name[pkt.len] = '\0';
dput(dentry);
if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire))) if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
ret = -EFAULT; ret = -EFAULT;
...@@ -609,6 +608,8 @@ int autofs_expire_run(struct super_block *sb, ...@@ -609,6 +608,8 @@ int autofs_expire_run(struct super_block *sb,
complete_all(&ino->expire_complete); complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock); spin_unlock(&sbi->fs_lock);
dput(dentry);
return ret; return ret;
} }
......
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