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Re: [Qemu-devel] [PATCH 0/2] linux-user: Fix length handling in cmsg con
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] linux-user: Fix length handling in cmsg conversions |
Date: |
Fri, 5 Jun 2015 16:03:17 +0100 |
Ping?
thanks
-- PMM
On 26 May 2015 at 19:46, Peter Maydell <address@hidden> wrote:
> This patchset fixes some problems in conversions of cmsg structures
> in target_to_host_cmsg() (used in send/recvmsg handling). Specifically:
>
> * we required the msg->msg_controllen to declare the buffer
> to have enough space for final trailing padding (we were
> checking against CMSG_SPACE), whereas the kernel does not
> require this, and common userspace code assumes this.
> * we weren't correctly handling the fact that the SO_TIMESTAMP
> payload may be larger for the target than the host
> * we weren't marking the messages with MSG_CTRUNC when we did
> need to truncate a message that wasn't truncated by the host,
> but were instead logging a QEMU message; since truncation is
> always the result of a guest giving us an insufficiently
> sized buffer, we should report it to the guest as the kernel
> does and don't log anything
> * we weren't handling the possibility of the host having a
> more restrictive alignment requirement for payload structs
>
> The major visible issue I wanted to fix is that glibc's "try to talk
> to nscd" code that it will run on startup will receive a cmsg with a
> 4 byte payload and only allocates 4 bytes for it, which was causing
> us to do the wrong thing on architectures that need 8-alignment
> (we dropped the cmsg and printed a diagnostic message).
>
>
> Peter Maydell (2):
> linux-user: Fix length handling in host_to_target_cmsg
> linux-user: use __get_user and __put_user in cmsg conversions
>
> linux-user/syscall.c | 89
> ++++++++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 72 insertions(+), 17 deletions(-)
>
> --
> 1.9.1
- Re: [Qemu-devel] [PATCH 0/2] linux-user: Fix length handling in cmsg conversions,
Peter Maydell <=