resource leak in /net/tap.c

[yuanjungong]

Hi,there might be a resource leak in function net_init_tap in /net/tap.c. The version is 5.1.91.

 811 fd = monitor_fd_param(monitor_cur(), tap->fd, errp);
 812 if (fd == -1) {
 813 return -1;
 814 }
 815
 816 ret = qemu_try_set_nonblock(fd);
 817 if (ret < 0) {
 818 error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
 819 name, fd);
 820 return -1;
 821 }
 822
 823 vnet_hdr = tap_probe_vnet_hdr(fd, errp);
 824 if (vnet_hdr < 0) {
 825 close(fd);
 826 return -1;
 827 }
 828
 829 net_init_tap_one(tap, peer, "tap", name, NULL,
 830 script, downscript,
 831 vhostfdname, vnet_hdr, fd, &err);
 832 if (err) {
 833 error_propagate(errp, err);
 834 return -1;
 835 }

fd should be closed before return in line 820 and line 834, similar to the implementation in line 825.

[Alex Chen (zdchen)]

hi yuanjungong,
You can send a patch to qemu-devel mailing list(https://wiki.qemu.org/MailingLists) to fix this memleak according to https://wiki.qemu.org/Contribute/SubmitAPatch.

Thanks.

[Alex Chen (zdchen)]

Hi yuanjungong,

If you don't have time to submit a patch, can I submit a patch to fix it?

[yuanjungong (yjruc)]

A patch has been submitted at https://lists.nongnu.org/archive/html/qemu-trivial/2020-11/msg00355.html

[yuanjungong (yjruc)]

Hi Alex,

Thanks for offering to help, but I submitted a patch to the maillist yesterday. Thank you again.

[Peter Maydell (pmaydell)]

Hi -- the patch looks good to me, but it looks like you didn't send it to qemu-devel, only to qemu-trivial. Would you mind resending it to the right list, please? (You can cc qemu-trivial if you like, but all patches have to go to the main qemu-devel list, because systems like patchew https://patchew.org/QEMU/ and also many developers only read the main list.)

[Peter Maydell (pmaydell)]

Fix now in master for 5.2 as commit f012bec8909820390936

[Thomas Huth (th-huth)]

Released with QEMU v5.2.0.