* [RFC] netlink: check for NULL attribute in nla_parse_nested_deprecated
@ 2024-02-16 1:52 Stephen Hemminger
2024-02-19 12:56 ` Simon Horman
2024-02-19 19:13 ` Jakub Kicinski
0 siblings, 2 replies; 3+ messages in thread
From: Stephen Hemminger @ 2024-02-16 1:52 UTC (permalink / raw)
To: netdev; +Cc: Stephen Hemminger
Lots of code in network schedulers has the pattern:
if (!nla) {
NL_SET_ERR_MSG_MOD(extack, "missing attributes");
return -EINVAL;
}
err = nla_parse_nested_deprecated(tb, TCA_CSUM_MAX, nla, csum_policy,
NULL);
if (err < 0)
return err;
The check for nla being NULL can be moved into nla_parse_nested_deprecated().
Which simplifies lots of places.
This is safer and won't break other places since:
err = nla_parse_nested_deprecated(tb, TCA_XXXX, NULL, some_policy, NULL);
would have crashed kernel because nla_parse_deprecated derefences the nla
argument before calling __nla_parse.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
include/net/netlink.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index c19ff921b661..05d137283ab0 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1322,6 +1322,11 @@ static inline int nla_parse_nested_deprecated(struct nlattr *tb[], int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
+ if (!nla) {
+ NL_SET_ERR_MSG_MOD(extack, "missing attributes");
+ return -EINVAL;
+ }
+
return __nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy,
NL_VALIDATE_LIBERAL, extack);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC] netlink: check for NULL attribute in nla_parse_nested_deprecated
2024-02-16 1:52 [RFC] netlink: check for NULL attribute in nla_parse_nested_deprecated Stephen Hemminger
@ 2024-02-19 12:56 ` Simon Horman
2024-02-19 19:13 ` Jakub Kicinski
1 sibling, 0 replies; 3+ messages in thread
From: Simon Horman @ 2024-02-19 12:56 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: netdev
On Thu, Feb 15, 2024 at 05:52:48PM -0800, Stephen Hemminger wrote:
> Lots of code in network schedulers has the pattern:
> if (!nla) {
> NL_SET_ERR_MSG_MOD(extack, "missing attributes");
> return -EINVAL;
> }
>
> err = nla_parse_nested_deprecated(tb, TCA_CSUM_MAX, nla, csum_policy,
> NULL);
> if (err < 0)
> return err;
>
> The check for nla being NULL can be moved into nla_parse_nested_deprecated().
> Which simplifies lots of places.
>
> This is safer and won't break other places since:
> err = nla_parse_nested_deprecated(tb, TCA_XXXX, NULL, some_policy, NULL);
> would have crashed kernel because nla_parse_deprecated derefences the nla
> argument before calling __nla_parse.
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Hi Stephen,
this seems like a good approach to me.
Would you also plan to update the schedules at some point?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] netlink: check for NULL attribute in nla_parse_nested_deprecated
2024-02-16 1:52 [RFC] netlink: check for NULL attribute in nla_parse_nested_deprecated Stephen Hemminger
2024-02-19 12:56 ` Simon Horman
@ 2024-02-19 19:13 ` Jakub Kicinski
1 sibling, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2024-02-19 19:13 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: netdev
On Thu, 15 Feb 2024 17:52:48 -0800 Stephen Hemminger wrote:
> Lots of code in network schedulers has the pattern:
> if (!nla) {
> NL_SET_ERR_MSG_MOD(extack, "missing attributes");
> return -EINVAL;
> }
>
> err = nla_parse_nested_deprecated(tb, TCA_CSUM_MAX, nla, csum_policy,
> NULL);
> if (err < 0)
> return err;
>
> The check for nla being NULL can be moved into nla_parse_nested_deprecated().
> Which simplifies lots of places.
If it's mainly TC which has this problem the fix belongs in TC,
not in the generic code.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-02-19 12:56 ` Simon Horman
2024-02-19 19:13 ` Jakub Kicinski
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