diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2014-09-13 21:59:43 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2014-09-14 14:24:47 -0400 |
| commit | 4023bfc9f351a7994fb6a7d515476c320f94a574 (patch) | |
| tree | 6d913f5173ec88cbf8277cc25c33b4898b3ef467 /fs | |
| parent | 7bd88377d482e1eae3c5329b12e33cfd664fa6a9 (diff) | |
| download | lwn-4023bfc9f351a7994fb6a7d515476c320f94a574.tar.gz lwn-4023bfc9f351a7994fb6a7d515476c320f94a574.zip | |
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>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namei.c | 15 |
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) |