Re: [PATCH net-next-2.6] net: dev_addr_init() fix
From: Jiri Pirko <hidden>
Date: 2009-06-08 12:42:38
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Mon, Jun 08, 2009 at 02:13:32PM CEST, dada1@cosmosbay.com wrote:
Eric Dumazet a écrit :quoted
Vegard Nossum a écrit :quoted
2009/6/7 John Dykstra [off-list ref]:quoted
On Sat, 2009-05-30 at 22:23 +0200, Vegard Nossum wrote:quoted
It seems that loopback's hardware address is never initialized by the kernel. So if userspace attempts to read this address before it has been set, the kernel will return some uninitialized data (only 6 bytes, though).Thank you for the report, Vegard. I've been unable to reproduce the problem you describe, using 2.6-30-rc8, this test program and a couple of kernel builds for system load:[...]quoted
------------------------------------------------------------------ Looking at the kernel code, it appears that all bytes of struct net_device, including the L2 address, are initialized to zeros at interface creation time. Can you spot a difference between your test procedures and mine that would enable me to reproduce the problem?Hi, I just tried your test program on a linux-next kernel, it works beautifully :-) (I made one change: The stack grows downwards on x86, so I think you should put child_stack + 16386 as the stack to clone()?) As I wrote in reply to Stephen Hemminger, this problem seems to be caused by a particular patch in linux-next: commit f001fde5eadd915f4858d22ed70d7040f48767cf Author: Jiri Pirko [off-list ref] Date: Tue May 5 02:48:28 2009 +0000 net: introduce a list of device addresses dev_addr_list (v6)I believe following patch should fix this problem. Thank you [PATCH net-next-2.6] net: loopback device dev->addr_len fix commit f001fde5eadd915f4858d22ed70d7040f48767cf (net: introduce a list of device addresses dev_addr_list (v6)) added one regression Vegard Nossum found in its testings. loopback device doesnt have a hw address, we should set its dev->addr_len to 0, not ETH_ALEN. Reported-by: Vegard Nossum <redacted> Signed-off-by: Eric Dumazet <redacted>
oops, sorry for this... Signed-off-by: Jiri Pirko <redacted>
quoted hunk ↗ jump to hunk
Oh well, following is probably even more appropriate [PATCH net-next-2.6] net: dev_addr_init() fix commit f001fde5eadd915f4858d22ed70d7040f48767cf (net: introduce a list of device addresses dev_addr_list (v6)) added one regression Vegard Nossum found in its testings. dev_addr_init() incorrectly uses sizeof() operator Reported-by: Vegard Nossum <redacted> Signed-off-by: Eric Dumazet <redacted> ---diff --git a/net/core/dev.c b/net/core/dev.c index 1f38401..65387d9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c@@ -3655,8 +3655,8 @@ static int dev_addr_init(struct net_device *dev)/* rtnl_mutex must be held here */ INIT_LIST_HEAD(&dev->dev_addr_list); - memset(addr, 0, sizeof(*addr)); - err = __hw_addr_add(&dev->dev_addr_list, NULL, addr, sizeof(*addr), + memset(addr, 0, sizeof(addr)); + err = __hw_addr_add(&dev->dev_addr_list, NULL, addr, sizeof(addr), NETDEV_HW_ADDR_T_LAN); if (!err) { /*