patchlwIP - A Lightweight TCP/IP stack - Patches: patch #10274, dhcp: limit number of dns servers...


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patch #10274: dhcp: limit number of dns servers we parse to LWIP_DHCP_PROVIDE_DNS_SERVERS

Submitter:  Matteo Fumagalli <matteofumagalli>
Submitted:  Wed 31 Aug 2022 07:52:22 AM UTC
Category:  DHCP Priority:  5 - Normal
Status:  None Privacy:  Public
Assigned to:  None Open/Closed:  Open
Planned Release:  None

Fri 09 Sep 2022 01:57:49 PM UTC, comment #1: 

As I can see this problem is already reported:
and here

Karol Domagalski <karol_domag>
Wed 31 Aug 2022 07:52:22 AM UTC, original submission:  


I met an issue in the following condition:


While connecting to a certain network i was getting 3 different DNS servers, but the code on the dhcp side tries to parse 4 entries instead of 2:

/* limit number of DNS servers */
decode_len = LWIP_MIN(len, 4 * DNS_MAX_SERVERS);

causing an assert at:

LWIP_ASSERT("check decode_idx", decode_idx >= 0 && decode_idx < DHCP_OPTION_IDX_MAX);

I think it's correct to use LWIP_DHCP_PROVIDE_DNS_SERVERS instead of DNS_MAX_SERVERS.

Let me know if i'm wrong. Currently i modified it like this to make it work.


Matteo Fumagalli <matteofumagalli>


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Depends on the following items: None found

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2022-08-31 matteofumagalli Attached File- Added 0001-dhcp-limit-number-of-dns-servers-we-parse-to-LWIP_DH.patch, #53641

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