On Thu, Oct 15, 2026 at 03:34:43AM +0200, Filip Hejsek wrote:
> Use qemu_dup() to ensure the cloexec flag is set on dup'd fds.
>
> The only direct users of dup() are now guest syscalls in the user
> emulators and the implementation of qemu_dup() itself.
>
> Signed-off-by: Filip Hejsek <[email protected]>
> ---
> For each call I replaced, I checked how the resulting fd is used
> afterwards. In summary:
>
> hw/virtio/virtio.c:
> the fd is passed to memory_region_init_ram_from_fd, used for mmaping
>
> io/channel-file.c:
> the fd is passed to qio_channel_file_new_fd, used for reading/writing
>
> migration/cpr-exec.c:
> the cloexec flag is cleared
>
> qemu-nbd.c:
> the fd is stored into old_stderr, then dup2'd back to STDERR_FILENO
>
> system/vl.c:
> no change in behavior, the code was already setting the cloexec flag
>
> ui/dmabuf.c:
> the function is called by qemu_spice_gl_update, which passes the fds
> to SPICE server
>
> tests/qtest/bios-tables-test.c:
> temp dup of stdout, dup2'd back to STDOUT_FILENO
>
> tests/unit/test-util-sockets.c:
> one fd is dup'd again and returned from mock monitor_get_fd; another
> is converted to string and given as address to socket_connect
>
> tests/unit/test-vmstate.c:
> passed to qio_channel_file_new_fd to create a channel
>
> Changes in v3:
> - Also replace the use in migration/cpr-exec.c and the tests
> - Link to v2:
> https://lore.kernel.org/qemu-devel/[email protected]
>
> Changes in v2:
> - Replace the use in qemu-nbd.c too
> - Changed commit message
> - Link to v1:
> https://lore.kernel.org/qemu-devel/[email protected]
> ---
> hw/virtio/virtio.c | 2 +-
> io/channel-file.c | 2 +-
> migration/cpr-exec.c | 2 +-
> qemu-nbd.c | 2 +-
> system/vl.c | 9 +--------
> tests/qtest/bios-tables-test.c | 2 +-
> tests/unit/test-util-sockets.c | 6 +++---
> tests/unit/test-vmstate.c | 2 +-
> ui/dmabuf.c | 2 +-
> 9 files changed, 11 insertions(+), 18 deletions(-)
> diff --git a/migration/cpr-exec.c b/migration/cpr-exec.c
> index daa50916d2..2f38db30bb 100644
> --- a/migration/cpr-exec.c
> +++ b/migration/cpr-exec.c
> @@ -44,7 +44,7 @@ bool cpr_exec_persist_state(QEMUFile *f, Error **errp)
> {
> QIOChannelFile *fioc = QIO_CHANNEL_FILE(qemu_file_get_ioc(f));
> /* coverity[leaked_storage] - mfd intentionally kept open across exec()
> */
> - int mfd = dup(fioc->fd);
> + int mfd = qemu_dup(fioc->fd);
> char val[16];
This change needed to be:
int mfd = qemu_dup(fioc->fd);
qemu_clear_cloexec(fioc->fd);
If that is added:
Reviewed-by: Daniel P. Berrangé <[email protected]>
With regards,
Daniel
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