[Qemu-devel] [PULL 0/1] Usb 20170720 patches

[Qemu-devel] [PULL 0/1] Usb 20170720 patches

[Gerd Hoffmann]

The following changes since commit d4e59218ab80e86015753782fb5378767a51ccd0:

  Merge remote-tracking branch 'remotes/berrange/tags/pull-qcrypto-2017-07-18-2' into staging (2017-07-19 20:45:37 +0100)

are available in the git repository at:

  git://git.kraxel.org/qemu tags/usb-20170720-pull-request

for you to fetch changes up to 121829cb2160e9cd82482c1542699fa589688106:

  usb: Fix build with newer gcc (2017-07-20 10:02:11 +0200)

----------------------------------------------------------------
usb: Fix build with newer gcc

----------------------------------------------------------------

Eric Blake (1):
  usb: Fix build with newer gcc

 hw/usb/bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

-- 
2.9.3

[Qemu-devel] [PULL 1/1] usb: Fix build with newer gcc

[Gerd Hoffmann]

From: Eric Blake <eblake@redhat.com>

gcc 7 is pickier about our sources:

hw/usb/bus.c: In function ‘usb_port_location’:
hw/usb/bus.c:410:66: error: ‘%d’ directive output may be truncated writing between 1 and 11 bytes into a region of size between 0 and 15 [-Werror=format-truncation=]
         snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
                                                                  ^~
hw/usb/bus.c:410:9: note: ‘snprintf’ output between 3 and 28 bytes into a destination of size 16
         snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  upstream->path, portnr);
                  ~~~~~~~~~~~~~~~~~~~~~~~

But we know that there are at most 5 levels of USB hubs, with at
most two digits per level; that plus the separating dots means we
use at most 15 bytes (including trailing NUL) of our 16-byte field.
Adding an assertion to show gcc that we checked for truncation is
enough to shut up the false-positive warning.

Inspired by an idea by Dr. David Alan Gilbert <dgilbert@redhat.com>.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170717151334.17954-1-eblake@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index 5939b273b9..d910f849e7 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -407,8 +407,10 @@ void usb_register_companion(const char *masterbus, USBPort *ports[],
 void usb_port_location(USBPort *downstream, USBPort *upstream, int portnr)
 {
     if (upstream) {
-        snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
-                 upstream->path, portnr);
+        int l = snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
+                         upstream->path, portnr);
+        /* Max string is nn.nn.nn.nn.nn, which fits in 16 bytes */
+        assert(l < sizeof(downstream->path));
         downstream->hubcount = upstream->hubcount + 1;
     } else {
         snprintf(downstream->path, sizeof(downstream->path), "%d", portnr);
-- 
2.9.3

Re: [Qemu-devel] [PULL 0/1] Usb 20170720 patches

[Peter Maydell]

On 20 July 2017 at 09:45, Gerd Hoffmann <kraxel@redhat.com> wrote:
> The following changes since commit d4e59218ab80e86015753782fb5378767a51ccd0:
>
>   Merge remote-tracking branch 'remotes/berrange/tags/pull-qcrypto-2017-07-18-2' into staging (2017-07-19 20:45:37 +0100)
>
> are available in the git repository at:
>
>   git://git.kraxel.org/qemu tags/usb-20170720-pull-request
>
> for you to fetch changes up to 121829cb2160e9cd82482c1542699fa589688106:
>
>   usb: Fix build with newer gcc (2017-07-20 10:02:11 +0200)
>
> ----------------------------------------------------------------
> usb: Fix build with newer gcc
>
> ----------------------------------------------------------------
>
> Eric Blake (1):
>   usb: Fix build with newer gcc
>
>  hw/usb/bus.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Applied, thanks.

-- PMM