4.9-stable review patch. If anyone has any objections, please let me know.
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[ 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... 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/autofs4/expire.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index d8e6d421c27f..2e1f50e467f1 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -563,7 +563,6 @@ int autofs4_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; @@ -576,6 +575,8 @@ int autofs4_expire_run(struct super_block *sb, complete_all(&ino->expire_complete); spin_unlock(&sbi->fs_lock);
+ dput(dentry); + return ret; }