2018-09-25 09:53:30

by Kirill Tkhai

Subject: [PATCH] fuse: Fix use-after-free in fuse_dev_do_write()

After we found req in request_find() and released the lock,
everything may happen with the req in parallel.

Keep it alive till we finish touch its memory.

Signed-off-by: Kirill Tkhai <[email protected]>
---
fs/fuse/dev.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 675caed3e655..c2af8042f176 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1877,16 +1877,20 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,

/* Is it an interrupt reply? */
if (req->intr_unique == oh.unique) {
+ __fuse_get_request(req);
spin_unlock(&fpq->lock);

err = -EINVAL;
- if (nbytes != sizeof(struct fuse_out_header))
+ if (nbytes != sizeof(struct fuse_out_header)) {
+ fuse_put_request(fc, req);
goto err_finish;
+ }

if (oh.error == -ENOSYS)
fc->no_interrupt = 1;
else if (oh.error == -EAGAIN)
queue_interrupt(&fc->iq, req);
+ fuse_put_request(fc, req);

fuse_copy_finish(cs);
return nbytes;

2018-10-01 09:27:08

by Miklos Szeredi

Subject: Re: [PATCH] fuse: Fix use-after-free in fuse_dev_do_write()

On Tue, Sep 25, 2018 at 11:52 AM, Kirill Tkhai <[email protected]> wrote:
> After we found req in request_find() and released the lock,
> everything may happen with the req in parallel.
>
> Keep it alive till we finish touch its memory.
>
> Signed-off-by: Kirill Tkhai <[email protected]>

Applied.

Thanks,
Miklos