Messages in this thread | | | Date | Thu, 7 Dec 2023 13:17:42 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v2 4/6] iommufd: Deliver fault messages to user space |
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On Thu, Dec 07, 2023 at 05:34:10PM +0100, Joel Granados wrote: > > @@ -58,6 +255,8 @@ static void hw_pagetable_fault_free(struct hw_pgtable_fault *fault) > > WARN_ON(!list_empty(&fault->deliver)); > > WARN_ON(!list_empty(&fault->response)); > > > > + fput(fault->fault_file); > > + put_unused_fd(fault->fault_fd);
> I have resolved this in a naive way by just not calling the > put_unused_fd function.
That is correct.
put_unused_fd() should only be called on error paths prior to the syscall return.
The design of a FD must follow this pattern
syscall(): fdno = get_unused_fd_flags(O_CLOEXEC); filep = [..]
// syscall MUST succeed after this statement: fd_install(fdno, filep); return 0;
err: put_unused_fd(fdno) return -ERRNO
Also the refcounting looks a little strange, the filep reference is consumed by fd_install, so what is that fput pairing with in fault_free?
Jason
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