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Date: Sun, 11 Nov 2018 19:49:05 +0000
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org,
"Tetsuo Handa" <penguin-kernel@...ove.SAKURA.ne.jp>,
"Miklos Szeredi" <mszeredi@...hat.com>,
"syzbot" <syzbot+ec3986119086fe4eec97@...kaller.appspotmail.com>,
"Anand Avati" <avati@...hat.com>, "Csaba Henk" <csaba@...ster.com>,
"John Muir" <john@...ir.com>
Subject: [PATCH 3.16 101/366] fuse: don't keep dead fuse_conn at
fuse_fill_super().
3.16.61-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Tetsuo Handa <penguin-kernel@...ove.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=a07a680ed0a9290585ca424546860464dd9658db
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+ec3986119086fe4eec97@...kaller.appspotmail.com>
Fixes: 3b463ae0c626 ("fuse: invalidation reverse calls")
Cc: John Muir <john@...ir.com>
Cc: Csaba Henk <csaba@...ster.com>
Cc: Anand Avati <avati@...hat.com>
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
fs/fuse/inode.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1125,6 +1125,7 @@ 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:
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