4.4-stable review patch. If anyone has any objections, please let me know.
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From: Kirill Tkhai ktkhai@virtuozzo.com
commit bc78abbd55dd28e2287ec6d6502b842321a17c87 upstream.
We may pick freed req in this way:
[cpu0] [cpu1] fuse_dev_do_read() fuse_dev_do_write() list_move_tail(&req->list, ...); ... spin_unlock(&fpq->lock); ... ... request_end(fc, req); ... fuse_put_request(fc, req); if (test_bit(FR_INTERRUPTED, ...)) queue_interrupt(fiq, req);
Fix that by keeping req alive until we finish all manipulations.
Reported-by: syzbot+4e975615ca01f2277bdd@syzkaller.appspotmail.com Signed-off-by: Kirill Tkhai ktkhai@virtuozzo.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Fixes: 46c34a348b0a ("fuse: no fc->lock for pqueue parts") Cc: stable@vger.kernel.org # v4.2 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/fuse/dev.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1328,12 +1328,14 @@ static ssize_t fuse_dev_do_read(struct f 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;