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authorMiklos Szeredi <mszeredi@redhat.com>2018-05-31 13:26:10 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2018-05-31 13:26:10 +0300
commit6becdb601bae2a043d7fb9762c4d48699528ea6e (patch)
tree7d136a357c374a82bb8e329811d84af96a920a36 /fs/fuse
parent8a301eb16d99983a4961f884690ec97b92e7dcfe (diff)
downloadlinux-6becdb601bae2a043d7fb9762c4d48699528ea6e.tar.xz
fuse: fix control dir setup and teardown
syzbot is reporting NULL pointer dereference at fuse_ctl_remove_conn() [1]. Since fc->ctl_ndents is incremented by fuse_ctl_add_conn() when new_inode() failed, fuse_ctl_remove_conn() reaches an inode-less dentry and tries to clear d_inode(dentry)->i_private field. Fix by only adding the dentry to the array after being fully set up. When tearing down the control directory, do d_invalidate() on it to get rid of any mounts that might have been added. [1] https://syzkaller.appspot.com/bug?id=f396d863067238959c91c0b7cfc10b163638cac6 Reported-by: syzbot <syzbot+32c236387d66c4516827@syzkaller.appspotmail.com> Fixes: bafa96541b25 ("[PATCH] fuse: add control filesystem") Cc: <stable@vger.kernel.org> # v2.6.18 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/control.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 78fb7a07c5ca..0b694655d988 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -211,10 +211,11 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
if (!dentry)
return NULL;
- fc->ctl_dentry[fc->ctl_ndents++] = dentry;
inode = new_inode(fuse_control_sb);
- if (!inode)
+ if (!inode) {
+ dput(dentry);
return NULL;
+ }
inode->i_ino = get_next_ino();
inode->i_mode = mode;
@@ -228,6 +229,9 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
set_nlink(inode, nlink);
inode->i_private = fc;
d_add(dentry, inode);
+
+ fc->ctl_dentry[fc->ctl_ndents++] = dentry;
+
return dentry;
}
@@ -284,7 +288,10 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc)
for (i = fc->ctl_ndents - 1; i >= 0; i--) {
struct dentry *dentry = fc->ctl_dentry[i];
d_inode(dentry)->i_private = NULL;
- d_drop(dentry);
+ if (!i) {
+ /* Get rid of submounts: */
+ d_invalidate(dentry);
+ }
dput(dentry);
}
drop_nlink(d_inode(fuse_control_sb->s_root));