diff mbox

fuse: don't keep dead fuse_conn at fuse_fill_super().

Message ID cfafbb9a-9e47-2489-8c71-9a6bc0d40e80@I-love.SAKURA.ne.jp (mailing list archive)
State New, archived
Headers show

Commit Message

Tetsuo Handa May 9, 2018, 11:01 a.m. UTC 
From 606d54cd24b5b00e7a7e3597aabbe89719defc56 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Tue, 1 May 2018 13:12:14 +0900
Subject: [PATCH] fuse: don't keep dead fuse_conn at fuse_fill_super().

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=a07a680ed0a9290585ca424546860464dd9658db

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com>
Fixes: 3b463ae0c6264f70 ("fuse: invalidation reverse calls")
Cc: John Muir <john@jmuir.com>
Cc: Csaba Henk <csaba@gluster.com>
Cc: Anand Avati <avati@redhat.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/fuse/inode.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Tetsuo Handa May 19, 2018, 2:03 p.m. UTC | #1 
Not yet applied to fuse.git. But I assume it will be applied by Miklos...

#syz fix: fuse: don't keep dead fuse_conn at fuse_fill_super().
Miklos Szeredi May 31, 2018, 10:19 a.m. UTC | #2 
On Wed, May 9, 2018 at 1:01 PM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> From 606d54cd24b5b00e7a7e3597aabbe89719defc56 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Date: Tue, 1 May 2018 13:12:14 +0900
> Subject: [PATCH] fuse: don't keep dead fuse_conn at fuse_fill_super().
>
> 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().

Thanks, applied.

Miklos
diff mbox

Patch

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index ef30995..9b37cf8 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1179,6 +1179,7 @@  static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 	fuse_dev_free(fud);
  err_put_conn:
 	fuse_conn_put(fc);
+	sb->s_fs_info = NULL;
  err_fput:
 	fput(file);
  err: