From: Al Viro Date: Sun, 5 Jun 2016 04:23:09 +0000 (-0400) Subject: autofs braino fix for do_last() X-Git-Tag: v4.6.5~163 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=21eb7f2839e4384550cc1f5132b5590f52405f1d;p=thirdparty%2Fkernel%2Fstable.git autofs braino fix for do_last() commit e6ec03a25f12b312b7e0c037fe4a6471c4ee5665 upstream. It's an analogue of commit 7500c38a (fix the braino in "namei: massage lookup_slow() to be usable by lookup_one_len_unlocked()"). The same problem (->lookup()-returned unhashed negative dentry just might be an autofs one with ->d_manage() that would wait until the daemon makes it positive) applies in do_last() - we need to do follow_managed() first. Fortunately, remaining callers of follow_managed() are OK - only autofs has that weirdness (negative dentry that does not mean an instant -ENOENT)) and autofs never has its negative dentries hashed, so we can't pick one from a dcache lookup. ->d_manage() is a bloody mess ;-/ Spotted-by: Ian Kent Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/namei.c b/fs/namei.c index 30145f8f21ed5..aaa3b693ec0b8 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3173,6 +3173,10 @@ retry_lookup: got_write = false; } + error = follow_managed(&path, nd); + if (unlikely(error < 0)) + return error; + if (unlikely(d_is_negative(path.dentry))) { path_to_nameidata(&path, nd); return -ENOENT; @@ -3188,10 +3192,6 @@ retry_lookup: return -EEXIST; } - error = follow_managed(&path, nd); - if (unlikely(error < 0)) - return error; - seq = 0; /* out of RCU mode, so the value doesn't matter */ inode = d_backing_inode(path.dentry); finish_lookup: