afs: Fix use-after-loss-of-ref
afs_lookup() has a tracepoint to indicate the outcome of
d_splice_alias(), passing it the inode to retrieve the fid from.
However, the function gave up its ref on that inode when it called
d_splice_alias(), which may have failed and dropped the inode.
Fix this by caching the fid.
Fixes: 80548b03991f ("afs: Add more tracepoints")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 497f979..813db17 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -908,6 +908,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct afs_vnode *dvnode = AFS_FS_I(dir);
+ struct afs_fid fid = {};
struct inode *inode;
struct dentry *d;
struct key *key;
@@ -957,15 +958,16 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
dentry->d_fsdata =
(void *)(unsigned long)dvnode->status.data_version;
}
+
+ if (!IS_ERR_OR_NULL(inode))
+ fid = AFS_FS_I(inode)->fid;
+
d = d_splice_alias(inode, dentry);
if (!IS_ERR_OR_NULL(d)) {
d->d_fsdata = dentry->d_fsdata;
- trace_afs_lookup(dvnode, &d->d_name,
- inode ? AFS_FS_I(inode) : NULL);
+ trace_afs_lookup(dvnode, &d->d_name, &fid);
} else {
- trace_afs_lookup(dvnode, &dentry->d_name,
- IS_ERR_OR_NULL(inode) ? NULL
- : AFS_FS_I(inode));
+ trace_afs_lookup(dvnode, &dentry->d_name, &fid);
}
return d;
}