* [PATCH 1/1] ar7: replace mac address parsing
@ 2014-06-24 15:39 Daniel Walter
2014-06-24 15:48 ` Joe Perches
0 siblings, 1 reply; 6+ messages in thread
From: Daniel Walter @ 2014-06-24 15:39 UTC (permalink / raw)
To: Ralf Baechle; +Cc: linux-mips, linux-kernel
Replace sscanf() with mac_pton().
Signed-off-by: Daniel Walter <dwalter@google.com>
---
arch/mips/ar7/platform.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
---
diff --git a/arch/mips/ar7/platform.c b/arch/mips/ar7/platform.c
index 7e2356f..653cbff 100644
--- a/arch/mips/ar7/platform.c
+++ b/arch/mips/ar7/platform.c
@@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
}
if (mac) {
- if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
- &dev_addr[0], &dev_addr[1],
- &dev_addr[2], &dev_addr[3],
- &dev_addr[4], &dev_addr[5]) != 6) {
+ if (!mac_pton(mac, dev_addr)) {
pr_warning("cannot parse mac address, "
"using random address\n");
eth_random_addr(dev_addr);
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] ar7: replace mac address parsing
2014-06-24 15:39 [PATCH 1/1] ar7: replace mac address parsing Daniel Walter
@ 2014-06-24 15:48 ` Joe Perches
2014-06-24 19:26 ` Florian Fainelli
0 siblings, 1 reply; 6+ messages in thread
From: Joe Perches @ 2014-06-24 15:48 UTC (permalink / raw)
To: Daniel Walter; +Cc: Ralf Baechle, linux-mips, linux-kernel
On Tue, 2014-06-24 at 16:39 +0100, Daniel Walter wrote:
> Replace sscanf() with mac_pton().
[]
> diff --git a/arch/mips/ar7/platform.c b/arch/mips/ar7/platform.c
[]
> @@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
> }
>
> if (mac) {
> - if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
> - &dev_addr[0], &dev_addr[1],
> - &dev_addr[2], &dev_addr[3],
> - &dev_addr[4], &dev_addr[5]) != 6) {
> + if (!mac_pton(mac, dev_addr)) {
There is a slight functional change with this conversion.
mac_pton is strict about leading 0's and requires a 17 char strlen.
sscanf will accept 0:1:2:3:4:5, mac_pton will not.
> pr_warning("cannot parse mac address, "
> "using random address\n");
could be coalesced and pr_warn
pr_warn("cannot parse mac address - using random address\n");
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] ar7: replace mac address parsing
2014-06-24 15:48 ` Joe Perches
@ 2014-06-24 19:26 ` Florian Fainelli
2015-04-01 12:17 ` Jonas Gorski
0 siblings, 1 reply; 6+ messages in thread
From: Florian Fainelli @ 2014-06-24 19:26 UTC (permalink / raw)
To: Joe Perches; +Cc: Daniel Walter, Ralf Baechle, Linux-MIPS, linux-kernel
2014-06-24 8:48 GMT-07:00 Joe Perches <joe@perches.com>:
> On Tue, 2014-06-24 at 16:39 +0100, Daniel Walter wrote:
>> Replace sscanf() with mac_pton().
> []
>> diff --git a/arch/mips/ar7/platform.c b/arch/mips/ar7/platform.c
> []
>> @@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
>> }
>>
>> if (mac) {
>> - if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
>> - &dev_addr[0], &dev_addr[1],
>> - &dev_addr[2], &dev_addr[3],
>> - &dev_addr[4], &dev_addr[5]) != 6) {
>> + if (!mac_pton(mac, dev_addr)) {
>
> There is a slight functional change with this conversion.
>
> mac_pton is strict about leading 0's and requires a 17 char strlen.
I do not have my devices handy, but I am fairly positive the use of
sscanf() was exactly for that, we may or may not have leading zeroes.
I am feeling a little uncomfortable with random code changes like that
without being actually able to test on real hardware that has a
variety of bootloaders and environment variables.
>
> sscanf will accept 0:1:2:3:4:5, mac_pton will not.
>
>> pr_warning("cannot parse mac address, "
>> "using random address\n");
>
> could be coalesced and pr_warn
>
> pr_warn("cannot parse mac address - using random address\n");
>
>
>
--
Florian
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] ar7: replace mac address parsing
2014-06-24 19:26 ` Florian Fainelli
@ 2015-04-01 12:17 ` Jonas Gorski
2015-04-01 15:08 ` Ralf Baechle
2015-04-01 18:05 ` Joe Perches
0 siblings, 2 replies; 6+ messages in thread
From: Jonas Gorski @ 2015-04-01 12:17 UTC (permalink / raw)
To: Florian Fainelli
Cc: Joe Perches, Daniel Walter, Ralf Baechle, Linux-MIPS, linux-kernel
On Tue, Jun 24, 2014 at 9:26 PM, Florian Fainelli <florian@openwrt.org> wrote:
> 2014-06-24 8:48 GMT-07:00 Joe Perches <joe@perches.com>:
>> On Tue, 2014-06-24 at 16:39 +0100, Daniel Walter wrote:
>>> Replace sscanf() with mac_pton().
>> []
>>> diff --git a/arch/mips/ar7/platform.c b/arch/mips/ar7/platform.c
>> []
>>> @@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
>>> }
>>>
>>> if (mac) {
>>> - if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
>>> - &dev_addr[0], &dev_addr[1],
>>> - &dev_addr[2], &dev_addr[3],
>>> - &dev_addr[4], &dev_addr[5]) != 6) {
>>> + if (!mac_pton(mac, dev_addr)) {
>>
>> There is a slight functional change with this conversion.
>>
>> mac_pton is strict about leading 0's and requires a 17 char strlen.
>
> I do not have my devices handy, but I am fairly positive the use of
> sscanf() was exactly for that, we may or may not have leading zeroes.
> I am feeling a little uncomfortable with random code changes like that
> without being actually able to test on real hardware that has a
> variety of bootloaders and environment variables.
One of my two devices has a mac address with one of the numbers being
< 16, and it uses a fixed length mac:
(psbl) printenv
...
HWA_0 00:16:B6:2A:A4:3B
Also looking at the history[1] of this code, it looks like this was
just an optimization of an earlier code which did expect 17 char len:
for (i = 0; i < 6; i++)
dev_addr[i] = (char2hex(mac[i * 3]) << 4) +
char2hex(mac[i * 3 + 1]);
So I'm tempted to say it should not cause any issues. But my sample
size is rather small.
Regards
Jonas
[1] d16f7093b6eb4f3859856f6ee4ab504cbeeea0b9
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] ar7: replace mac address parsing
2015-04-01 12:17 ` Jonas Gorski
@ 2015-04-01 15:08 ` Ralf Baechle
2015-04-01 18:05 ` Joe Perches
1 sibling, 0 replies; 6+ messages in thread
From: Ralf Baechle @ 2015-04-01 15:08 UTC (permalink / raw)
To: Jonas Gorski
Cc: Florian Fainelli, Joe Perches, Daniel Walter, Linux-MIPS, linux-kernel
On Wed, Apr 01, 2015 at 02:17:16PM +0200, Jonas Gorski wrote:
> for (i = 0; i < 6; i++)
> dev_addr[i] = (char2hex(mac[i * 3]) << 4) +
> char2hex(mac[i * 3 + 1]);
>
>
> So I'm tempted to say it should not cause any issues. But my sample
> size is rather small.
4.1 is still long enough out to test ...
Ralf
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] ar7: replace mac address parsing
2015-04-01 12:17 ` Jonas Gorski
2015-04-01 15:08 ` Ralf Baechle
@ 2015-04-01 18:05 ` Joe Perches
1 sibling, 0 replies; 6+ messages in thread
From: Joe Perches @ 2015-04-01 18:05 UTC (permalink / raw)
To: Jonas Gorski
Cc: Florian Fainelli, Daniel Walter, Ralf Baechle, Linux-MIPS, linux-kernel
On Wed, 2015-04-01 at 14:17 +0200, Jonas Gorski wrote:
> On Tue, Jun 24, 2014 at 9:26 PM, Florian Fainelli <florian@openwrt.org> wrote:
> > 2014-06-24 8:48 GMT-07:00 Joe Perches <joe@perches.com>:
> >> On Tue, 2014-06-24 at 16:39 +0100, Daniel Walter wrote:
> >>> Replace sscanf() with mac_pton().
> >> []
> >>> diff --git a/arch/mips/ar7/platform.c b/arch/mips/ar7/platform.c
> >> []
> >>> @@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
> >>> }
> >>>
> >>> if (mac) {
> >>> - if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
> >>> - &dev_addr[0], &dev_addr[1],
> >>> - &dev_addr[2], &dev_addr[3],
> >>> - &dev_addr[4], &dev_addr[5]) != 6) {
> >>> + if (!mac_pton(mac, dev_addr)) {
> >>
> >> There is a slight functional change with this conversion.
> >>
> >> mac_pton is strict about leading 0's and requires a 17 char strlen.
> >
> > I do not have my devices handy, but I am fairly positive the use of
> > sscanf() was exactly for that, we may or may not have leading zeroes.
> > I am feeling a little uncomfortable with random code changes like that
> > without being actually able to test on real hardware that has a
> > variety of bootloaders and environment variables.
>
> One of my two devices has a mac address with one of the numbers being
> < 16, and it uses a fixed length mac:
>
> (psbl) printenv
> ...
> HWA_0 00:16:B6:2A:A4:3B
>
> Also looking at the history[1] of this code, it looks like this was
> just an optimization of an earlier code which did expect 17 char len:
>
> for (i = 0; i < 6; i++)
> dev_addr[i] = (char2hex(mac[i * 3]) << 4) +
> char2hex(mac[i * 3 + 1]);
>
>
> So I'm tempted to say it should not cause any issues. But my sample
> size is rather small.
> [1] d16f7093b6eb4f3859856f6ee4ab504cbeeea0b9
Wow Jonas, a 9 month thread gestation...
Given the old code and the commit comment, I'd
say it was almost certainly safe and my issue with
the patch resolved.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-04-01 18:05 UTC | newest]
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2014-06-24 15:39 [PATCH 1/1] ar7: replace mac address parsing Daniel Walter
2014-06-24 15:48 ` Joe Perches
2014-06-24 19:26 ` Florian Fainelli
2015-04-01 12:17 ` Jonas Gorski
2015-04-01 15:08 ` Ralf Baechle
2015-04-01 18:05 ` Joe Perches
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