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authorAl Viro <viro@zeniv.linux.org.uk>2015-05-07 19:24:57 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2015-05-09 00:12:35 -0400
commit766c4cbfacd8634d7580bac6a1b8456e63de3e84 (patch)
tree0bdde729de49ac95858f5429b40419b643fcc1cb
parent5ebe6afaf0057ac3eaeb98defd5456894b446d22 (diff)
downloadlinux-stericsson-766c4cbfacd8634d7580bac6a1b8456e63de3e84.tar.gz
namei: d_is_negative() should be checked before ->d_seq validation
Fetching ->d_inode, verifying ->d_seq and finding d_is_negative() to be true does *not* mean that inode we'd fetched had been NULL - that holds only while ->d_seq is still unchanged. Shift d_is_negative() checks into lookup_fast() prior to ->d_seq verification. Reported-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/namei.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 4a8d998b7274..f67cf6cef986 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1415,6 +1415,7 @@ static int lookup_fast(struct nameidata *nd,
*/
if (nd->flags & LOOKUP_RCU) {
unsigned seq;
+ bool negative;
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
if (!dentry)
goto unlazy;
@@ -1424,8 +1425,11 @@ static int lookup_fast(struct nameidata *nd,
* the dentry name information from lookup.
*/
*inode = dentry->d_inode;
+ negative = d_is_negative(dentry);
if (read_seqcount_retry(&dentry->d_seq, seq))
return -ECHILD;
+ if (negative)
+ return -ENOENT;
/*
* This sequence count validates that the parent had no
@@ -1472,6 +1476,10 @@ unlazy:
goto need_lookup;
}
+ if (unlikely(d_is_negative(dentry))) {
+ dput(dentry);
+ return -ENOENT;
+ }
path->mnt = mnt;
path->dentry = dentry;
err = follow_managed(path, nd->flags);
@@ -1583,10 +1591,10 @@ static inline int walk_component(struct nameidata *nd, struct path *path,
goto out_err;
inode = path->dentry->d_inode;
+ err = -ENOENT;
+ if (d_is_negative(path->dentry))
+ goto out_path_put;
}
- err = -ENOENT;
- if (d_is_negative(path->dentry))
- goto out_path_put;
if (should_follow_link(path->dentry, follow)) {
if (nd->flags & LOOKUP_RCU) {
@@ -3036,14 +3044,13 @@ retry_lookup:
BUG_ON(nd->flags & LOOKUP_RCU);
inode = path->dentry->d_inode;
-finish_lookup:
- /* we _can_ be in RCU mode here */
error = -ENOENT;
if (d_is_negative(path->dentry)) {
path_to_nameidata(path, nd);
goto out;
}
-
+finish_lookup:
+ /* we _can_ be in RCU mode here */
if (should_follow_link(path->dentry, !symlink_ok)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(nd->path.mnt != path->mnt ||