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* [PATCH] Infiniband: Fix potential NULL d_inode dereference
@ 2015-01-27 15:01 David Howells
  0 siblings, 0 replies; only message in thread
From: David Howells @ 2015-01-27 15:01 UTC (permalink / raw)
  Cc: infinipath, linux-rdma, linux-kernel, dhowells,
	Bryan O'Sullivan, viro, Roland Dreier

Code that does this:

	if (!(d_unhashed(tmp) && tmp->d_inode)) {
		...
		simple_unlink(parent->d_inode, tmp);
	}

is broken because:

	!(d_unhashed(tmp) && tmp->d_inode)

is equivalent to:

	!d_unhashed(tmp) || !tmp->d_inode

so it is possible to get into simple_unlink() with tmp->d_inode == NULL.

simple_unlink(), however, assumes tmp->d_inode cannot be NULL.

I think that what was meant is this:

	!d_unhashed(tmp) && tmp->d_inode

and that the logical-not operator or the final close-bracket was misplaced.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Bryan O'Sullivan <bos@pathscale.com>
cc: Roland Dreier <rolandd@cisco.com>
---

 drivers/infiniband/hw/ipath/ipath_fs.c |    2 +-
 drivers/infiniband/hw/qib/qib_fs.c     |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/ipath/ipath_fs.c b/drivers/infiniband/hw/ipath/ipath_fs.c
index 4977082e081f..33c45dfcbd88 100644
--- a/drivers/infiniband/hw/ipath/ipath_fs.c
+++ b/drivers/infiniband/hw/ipath/ipath_fs.c
@@ -277,7 +277,7 @@ static int remove_file(struct dentry *parent, char *name)
 	}
 
 	spin_lock(&tmp->d_lock);
-	if (!(d_unhashed(tmp) && tmp->d_inode)) {
+	if (!d_unhashed(tmp) && tmp->d_inode) {
 		dget_dlock(tmp);
 		__d_drop(tmp);
 		spin_unlock(&tmp->d_lock);
diff --git a/drivers/infiniband/hw/qib/qib_fs.c b/drivers/infiniband/hw/qib/qib_fs.c
index 81854586c081..d2427640d7e9 100644
--- a/drivers/infiniband/hw/qib/qib_fs.c
+++ b/drivers/infiniband/hw/qib/qib_fs.c
@@ -455,7 +455,7 @@ static int remove_file(struct dentry *parent, char *name)
 	}
 
 	spin_lock(&tmp->d_lock);
-	if (!(d_unhashed(tmp) && tmp->d_inode)) {
+	if (!d_unhashed(tmp) && tmp->d_inode) {
 		__d_drop(tmp);
 		spin_unlock(&tmp->d_lock);
 		simple_unlink(parent->d_inode, tmp);


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