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| author |   Al Viro <viro@zeniv.linux.org.uk> | 2015-05-07 19:24:57 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-09 00:12:35 -0400 |
| commit | 766c4cbfacd8634d7580bac6a1b8456e63de3e84 (patch) | |
| tree | 0bdde729de49ac95858f5429b40419b643fcc1cb /fs | |
| parent | Linux 4.1-rc2 (diff) | |
| download | linux-dev-766c4cbfacd8634d7580bac6a1b8456e63de3e84.tar.xz linux-dev-766c4cbfacd8634d7580bac6a1b8456e63de3e84.zip | |
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>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namei.c | 19 |
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 || |