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authorAl Viro <viro@zeniv.linux.org.uk>2014-09-13 21:59:43 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-09-14 14:24:47 -0400
commit4023bfc9f351a7994fb6a7d515476c320f94a574 (patch)
tree6d913f5173ec88cbf8277cc25c33b4898b3ef467
parent7bd88377d482e1eae3c5329b12e33cfd664fa6a9 (diff)
be careful with nd->inode in path_init() and follow_dotdot_rcu()
in the former we simply check if dentry is still valid after picking its ->d_inode; in the latter we fetch ->d_inode in the same places where we fetch dentry and its ->d_seq, under the same checks. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/namei.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/fs/namei.c b/fs/namei.c
index fe47e6d8e85f..d07bc1b206c3 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1142,6 +1142,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
static int follow_dotdot_rcu(struct nameidata *nd)
{
+ struct inode *inode = nd->inode;
if (!nd->root.mnt)
set_root_rcu(nd);
@@ -1155,6 +1156,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
struct dentry *parent = old->d_parent;
unsigned seq;
+ inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
if (read_seqcount_retry(&old->d_seq, nd->seq))
goto failed;
@@ -1164,6 +1166,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
}
if (!follow_up_rcu(&nd->path))
break;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
while (d_mountpoint(nd->path.dentry)) {
@@ -1173,11 +1176,12 @@ static int follow_dotdot_rcu(struct nameidata *nd)
break;
nd->path.mnt = &mounted->mnt;
nd->path.dentry = mounted->mnt.mnt_root;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
if (read_seqretry(&mount_lock, nd->m_seq))
goto failed;
}
- nd->inode = nd->path.dentry->d_inode;
+ nd->inode = inode;
return 0;
failed:
@@ -1904,7 +1908,14 @@ static int path_init(int dfd, const char *name, unsigned int flags,
}
nd->inode = nd->path.dentry->d_inode;
- return 0;
+ if (!(flags & LOOKUP_RCU))
+ return 0;
+ if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+ return 0;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ return -ECHILD;
}
static inline int lookup_last(struct nameidata *nd, struct path *path)