Re: [Patch net-next resend v2] net: use %px to print skb address in trace_netif_receive_skb
From: Kees Cook <hidden>
Date: 2021-07-23 07:09:21
Also in:
linux-hardening
On Wed, Jul 14, 2021 at 10:59:23PM -0700, Cong Wang wrote:
From: Qitao Xu <redacted> The print format of skb adress in tracepoint class net_dev_template is changed to %px from %p, because we want to use skb address as a quick way to identify a packet.
No; %p was already hashed to uniquely identify unique addresses. This is needlessly exposing kernel addresses with no change in utility. See [1] for full details on when %px is justified (almost never).
Note, trace ring buffer is only accessible to privileged users, it is safe to use a real kernel address here.
That's not accurate either; there is a difference between uid 0 and kernel mode privilege levels. Please revert these: 851f36e40962408309ad2665bf0056c19a97881c 65875073eddd24d7b3968c1501ef29277398dc7b And adjust this to replace %px with %p: 70713dddf3d25a02d1952f8c5d2688c986d2f2fb Thanks! -Kees [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#p-format-specifier
quoted hunk ↗ jump to hunk
Reviewed-by: Cong Wang <redacted> Signed-off-by: Qitao Xu <redacted> --- include/trace/events/net.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/include/trace/events/net.h b/include/trace/events/net.h index 2399073c3afc..78c448c6ab4c 100644 --- a/include/trace/events/net.h +++ b/include/trace/events/net.h@@ -136,7 +136,7 @@ DECLARE_EVENT_CLASS(net_dev_template, __assign_str(name, skb->dev->name); ), - TP_printk("dev=%s skbaddr=%p len=%u", + TP_printk("dev=%s skbaddr=%px len=%u", __get_str(name), __entry->skbaddr, __entry->len) )-- 2.27.0
-- Kees Cook