Re: [PATCH v4] net/tap-linux.c: avoid abort when setting invalid fd

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Nick,

On 25/9/25 04:32, Houqi (Nick) Zuo wrote:
> When QEMU creates a tap device automatically and the tap device is
> manually removed from the host while the guest is running, the tap
> device file descriptor becomes invalid. Later, when the guest executes
> shutdown, the tap_fd_set_vnet_hdr_len() function may be called and
> abort QEMU with a core dump when attempting to use the invalid fd.
> 
> This patch removes many abort() calls in this file. If the fd is found
> to be in a bad state (e.g., EBADFD or ENODEV), the related function
> will print an error message.
> 
> The expected behavior for this negative test case is that QEMU should
> report an error but continue running rather than aborting.


> Fixes: 0caed25cd171c611781589b5402161d27d57229c ("virtio: Call set_features during reset")
> 
> Signed-off-by: Houqi (Nick) Zuo <hzuo@redhat.com>
> ---
>   net/tap-linux.c | 13 ++++++++-----
>   1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/net/tap-linux.c b/net/tap-linux.c
> index e832810665..24e63a0b54 100644
> --- a/net/tap-linux.c
> +++ b/net/tap-linux.c
> @@ -206,15 +206,16 @@ void tap_fd_set_vnet_hdr_len(int fd, int len)
>       if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
>           fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
>                   strerror(errno));

Remove "Exiting".

While here, can you replace fprintf() -> error_report()?

> -        abort();

If we don't exit anymore, this function should return some value
indicating the failure, and the callers should check it.

>       }
>   }

Regards,

Phil.