Commit a1708203b5 for qemu.org

commit a1708203b583ec04fb9b793840dc282d3c89a20d
Author: Houqi (Nick) Zuo <hzuo@redhat.com>
Date:   Mon Dec 8 12:35:18 2025 +0800

    net/tap-linux.c: avoid abort when setting invalid fd

    This patch removes abort() call in the tap_fd_set_vnet_hdr_len()
    function. If the fd is found to be in a bad state (e.g., EBADFD
     or ENODEV), the function will print an error message.

    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.
    The expected behavior for this negative test case is that QEMU should
    report an error but continue running rather than aborting.

    Testing:
    - Start QEMU with automatically created tap device
    - Manually remove the tap device on the host
    - Execute shutdown in the guest
    - Verify QEMU reports an error but does not abort

    Fixes: 0caed25cd171 ("virtio: Call set_features during reset")
    Signed-off-by: Houqi (Nick) Zuo <hzuo@redhat.com>
    Signed-off-by: Jason Wang <jasowang@redhat.com>

diff --git a/net/tap-linux.c b/net/tap-linux.c
index 909c4f1fcf..54de3cd06b 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -214,10 +214,11 @@ bool tap_probe_has_tunnel(int fd)

 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));
-        abort();
+    int ret;
+
+    ret = ioctl(fd, TUNSETVNETHDRSZ, &len);
+    if (ret != 0) {
+        error_report("TUNSETVNETHDRSZ ioctl() failed: %s.", strerror(errno));
     }
 }