4.4-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit 543b8f8662fe6d21f19958b666ab0051af9db21a upstream.
syzbot is reporting use-after-free at fuse_kill_sb_blk() [1]. Since sb->s_fs_info field is not cleared after fc was released by fuse_conn_put() when initialization failed, fuse_kill_sb_blk() finds already released fc and tries to hold the lock. Fix this by clearing sb->s_fs_info field after calling fuse_conn_put().
[1] https://syzkaller.appspot.com/bug?id=a07a680ed0a9290585ca424546860464dd9658d...
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reported-by: syzbot syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com Fixes: 3b463ae0c626 ("fuse: invalidation reverse calls") Cc: John Muir john@jmuir.com Cc: Csaba Henk csaba@gluster.com Cc: Anand Avati avati@redhat.com Cc: stable@vger.kernel.org # v2.6.31 Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/fuse/inode.c | 1 + 1 file changed, 1 insertion(+)
--- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1158,6 +1158,7 @@ static int fuse_fill_super(struct super_ err_put_conn: fuse_bdi_destroy(fc); fuse_conn_put(fc); + sb->s_fs_info = NULL; err_fput: fput(file); err: