* [PATCH] fuse: Fix use-after-free in fuse_dev_do_read()
@ 2018-09-25 9:28 Kirill Tkhai
2018-10-01 9:25 ` Miklos Szeredi
0 siblings, 1 reply; 2+ messages in thread
From: Kirill Tkhai @ 2018-09-25 9:28 UTC (permalink / raw)
To: miklos, syzbot+4e975615ca01f2277bdd, linux-fsdevel, linux-kernel, ktkhai
We may pick freed req in this way:
[cpu0] [cpu1]
fuse_dev_do_read() fuse_dev_do_write()
list_move_tail(&req->list, &fpq->processing); ...
spin_unlock(&fpq->lock); ...
... request_end(fc, req);
... fuse_put_request(fc, req);
if (test_bit(FR_INTERRUPTED, &req->flags))
queue_interrupt(fiq, req);
Fix that by keeping req alive till we finish all manipulations.
Reported-by: syzbot+4e975615ca01f2277bdd@syzkaller.appspotmail.com
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
fs/fuse/dev.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 11ea2c4a38ab..675caed3e655 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1311,12 +1311,14 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
goto out_end;
}
list_move_tail(&req->list, &fpq->processing);
+ __fuse_get_request(req);
spin_unlock(&fpq->lock);
set_bit(FR_SENT, &req->flags);
/* matches barrier in request_wait_answer() */
smp_mb__after_atomic();
if (test_bit(FR_INTERRUPTED, &req->flags))
queue_interrupt(fiq, req);
+ fuse_put_request(fc, req);
return reqsize;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] fuse: Fix use-after-free in fuse_dev_do_read()
2018-09-25 9:28 [PATCH] fuse: Fix use-after-free in fuse_dev_do_read() Kirill Tkhai
@ 2018-10-01 9:25 ` Miklos Szeredi
0 siblings, 0 replies; 2+ messages in thread
From: Miklos Szeredi @ 2018-10-01 9:25 UTC (permalink / raw)
To: Kirill Tkhai; +Cc: syzbot, linux-fsdevel, linux-kernel
On Tue, Sep 25, 2018 at 11:28 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> We may pick freed req in this way:
>
> [cpu0] [cpu1]
> fuse_dev_do_read() fuse_dev_do_write()
> list_move_tail(&req->list, &fpq->processing); ...
> spin_unlock(&fpq->lock); ...
> ... request_end(fc, req);
> ... fuse_put_request(fc, req);
> if (test_bit(FR_INTERRUPTED, &req->flags))
> queue_interrupt(fiq, req);
>
> Fix that by keeping req alive till we finish all manipulations.
>
> Reported-by: syzbot+4e975615ca01f2277bdd@syzkaller.appspotmail.com
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Applied.
Thanks,
Miklos
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-09-25 9:28 [PATCH] fuse: Fix use-after-free in fuse_dev_do_read() Kirill Tkhai
2018-10-01 9:25 ` Miklos Szeredi
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