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fuse: clear FR_PENDING flag when moving requests out of pending queue 

fuse_abort_conn() moves requests from pending list to a temporary list
before canceling them. This operation races with request_wait_answer()
which also tries to remove the request after it gets a fatal signal. It
checks FR_PENDING flag to determine whether the request is still in the
pending list.

Make fuse_abort_conn() clear FR_PENDING flag so that request_wait_answer()
does not remove the request from temporary list.

This bug causes an Oops when trying to delete an already deleted list entry
in end_requests().

Fixes: ee314a870e ("fuse: abort: no fc->lock needed for request ending")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # 4.2+
hifive-unleashed-5.1
Tahsin Erdogan 2017-01-12 12:04:04 -08:00 committed by Miklos Szeredi
parent a121103c92
commit a8a86d78d6
1 changed files with 2 additions and 1 deletions
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3
fs/fuse/dev.c
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@ -2025,7 +2025,6 @@ static void end_requests(struct fuse_conn *fc, struct list_head *head)
struct fuse_req *req;
req = list_entry(head->next, struct fuse_req, list);
req->out.h.error = -ECONNABORTED;
clear_bit(FR_PENDING, &req->flags);
clear_bit(FR_SENT, &req->flags);
list_del_init(&req->list);
request_end(fc, req);
@ -2103,6 +2102,8 @@ void fuse_abort_conn(struct fuse_conn *fc)
spin_lock(&fiq->waitq.lock);
fiq->connected = 0;
list_splice_init(&fiq->pending, &to_end2);
list_for_each_entry(req, &to_end2, list)
clear_bit(FR_PENDING, &req->flags);
while (forget_pending(fiq))
kfree(dequeue_forget(fiq, 1, NULL));
wake_up_all_locked(&fiq->waitq);