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Re: [Qemu-arm] [PATCH] linux-user/syscall: let recvfrom(struct sockaddr
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-arm] [PATCH] linux-user/syscall: let recvfrom(struct sockaddr *) use abi_ulong |
Date: |
Tue, 23 Jan 2018 17:38:58 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
Le 23/01/2018 à 17:27, Guido Günther a écrit :
> Hi,
> On Tue, Jan 23, 2018 at 05:12:26PM +0100, Laurent Vivier wrote:
>> Le 23/01/2018 à 16:23, Guido Günther a écrit :
>>> Hi,
>>> Thanks for having a look!
>>>
>>> On Tue, Jan 23, 2018 at 11:52:22AM -0300, Philippe Mathieu-Daudé wrote:
>>>> Currently recvfrom() is restricted to handle 32-bit pointers,
>>>> remove this limit for 64-bit hosts.
>>>>
>>>> This fixes:
>>>>
>>>> 31572 socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = 3
>>>> ...
>>>> 31572 sendto(3, {{len=124, type=0x454 /* NLMSG_??? */,
>>>> flags=NLM_F_REQUEST|NLM_F_ACK, seq=1, pid=0}, "op=test:message acct=\"?\"
>>>> exe=\"/tmp/nl-bad-addr\" hostname=localhost addr=? terminal=/dev/pts/2
>>>> res=success\0\0\0"}, 124, 0, 0xfffffa3897d0, 0) = 124
>>>> 31572 ppoll([{fd=3, events=POLLIN}], 1, {tv_sec=0, tv_nsec=500000000},
>>>> NULL, 0) = 1 ([{fd=3, revents=POLLIN}], left {tv_sec=0, tv_nsec=499993180})
>>>> 31572 recvfrom(3, 0x112a50eb4, 8988, MSG_PEEK|MSG_DONTWAIT,
>>>> 0xfffffa3897e0, 0x42) = -1 EFAULT (Bad address)
...
>> Could you try:
>>
>> strace -f chroot . /usr/bin/qemu-arm-static tmp/nl-bad-addr
>>
>> to see if the fault comes from the kernel or from QEMU.
>
> Full strace is attached of
>
> strace -f -s2048 -onl-bad-addr.strace chroot armhf-chroot/
> tmp/qemu-arm-static tmp/a.out
>
> is attched. The error is at the very end.
...
> 9559 socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = 3
> 9559 fcntl(3, F_SETFD, FD_CLOEXEC) = 0
...
> 9559 sendto(3, {{len=120, type=0x454 /* NLMSG_??? */,
> flags=NLM_F_REQUEST|NLM_F_ACK, seq=1, pid=0}, "op=test:message acct=\"?\"
> exe=\"/tmp/a.out\" hostname=localhost addr=::1 terminal=/dev/pts/2
> res=success\0\0\0"}, 120, 0, 0xffffcdb29840, 0) = 120
> 9559 ppoll([{fd=3, events=POLLIN}], 1, {tv_sec=0, tv_nsec=500000000}, NULL,
> 0) = 1 ([{fd=3, revents=POLLIN}], left {tv_sec=0, tv_nsec=499951056})
> 9559 recvfrom(3, 0xffff9404ae84, 8988, MSG_PEEK|MSG_DONTWAIT,
> 0xffffcdb29850, 0x42) = -1 EFAULT (Bad address)
So the problem seems to be with the pointer/buffer we pass to the kernel
(either host_msg or addr). It's weird...
Thanks,
Laurent