On 31/01/18 06:20 AM, Paul Oranje wrote:
Why use a hard coded value 4 in "snprintf(devnum, 4, "%d", vldev->id);" ? Paul
Max value for a VLAN id is 4095 = 4 digits, although probably better would be to accept full length for int and truncate in the next line.
That and this was a quick hack to get around a compile error with GCC 2.7 (because of the buffer overrun), and not a fully formed patch; as stated, in the message this was more informational.
I suppose I should find some time and energy and submit a fully formed patch, unless someone gets there first.
Regards, Daniel
Op 30 jan. 2018, om 19:16 heeft csho...@thecshore.com het volgende geschreven: From: "Daniel F. Dickinson" <csho...@thecshore.com> Detected during a side project. Not a brilliant fix, but it gets the job done for now. *very* lightly tested, more for your information than anything else. Array out-of-bounds condition can occur because vlan device name is constructed from device name (size IFNAMSIZ) plus the ASCII decimal representation of the vlan id plus a dot, but the target can only be IFNAMSIZ. We fix this by using fields widths (and make sure we don't truncate more of the orogin device name than we must). Signed-off-by: Daniel F. Dickinson <csho...@thecshore.com> --- vlan.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/vlan.c b/vlan.c index 067f624..44852f4 100644 --- a/vlan.c +++ b/vlan.c @@ -63,10 +63,17 @@ static int vlan_set_device_state(struct device *dev, bool up) static void vlan_dev_set_name(struct vlan_device *vldev, struct device *dev) { - char name[IFNAMSIZ]; + char name[IFNAMSIZ + 1]; + char devnum[5]; + int i, j = 0; vldev->dev.hidden = dev->hidden; - snprintf(name, IFNAMSIZ, "%s.%d", dev->ifname, vldev->id); + snprintf(devnum, 4, "%d", vldev->id); + i = strnlen(devnum, 4); + j = IFNAMSIZ - i; + strncpy(name, dev->ifname, j); + strncat(name, ".", 1); + strncat(name, devnum, i); device_set_ifname(&vldev->dev, name); } -- 2.11.0 _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
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