bugGNU GRUB - Bugs: bug #46187, grub_net_tcp_accept always sends...


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bug #46187: grub_net_tcp_accept always sends SYN-ACK packets to all-zero mac

Submitted by:  Ignat Korchagin <ignat>
Submitted on:  Mon 12 Oct 2015 03:40:39 PM UTC  
Category:  Network Severity:  Major
Priority:  5 - Normal Item Group:  Software Error
Status:  Fixed Privacy:  Public
Assigned to:  None Originator Name:  Ignat Korchagin
Open/Closed:  Closed Release: 
Release:  Git master Reproducibility:  Every Time
Planned Release:  None

Thu 29 Oct 2015 03:31:02 PM UTC, comment #3: 

Committed. Thanks.

Vladimir Serbinenko <phcoder>
Project Administrator
Mon 26 Oct 2015 03:28:19 PM UTC, comment #2: 

Sorry for late reply, missed your comment.

Yes, we have custom code: I was experimenting with a module implementing a TCP server to listen for connections on boot and doing some early provisioning (for example, setting up secure boot keys). I noticed that TCP 3-way handshake always fail. After debugging, I noticed that L2 address never gets updated in the socket structure. After applying below patch everything (almost) worked like a charm.

Ignat Korchagin <ignat>
Mon 12 Oct 2015 07:52:12 PM UTC, comment #1: 

Do you have custom code using it? grub_net_tcp_accept is not really called anywhere.

Andrei Borzenkov <arvidjaar>
Project Member
Mon 12 Oct 2015 03:40:39 PM UTC, original submission:  

When using GRUB TCP in "server mode" there is no code to actually initialize remote mac address for the socket structure. This ends up GRUB sending SYN-ACK packets on all-zero mac in the socket structure and connection never gets accepted, since remote party never receives the SYN-ACK.
Since GRUB TCP client resolves remote link address on open, similar code was added to grub_net_tcp_accept.

Ignat Korchagin <ignat>


Attached Files
file #35169:  grub2.patch added by ignat (810B - text/x-patch)


Depends on the following items: None found

Items that depend on this one: None found


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  • -email is unavailable- added by phcoder (Posted a comment)
  • -email is unavailable- added by arvidjaar (Posted a comment)
  • -email is unavailable- added by ignat (Submitted the item)

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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-10-29 phcoder StatusNone => Fixed
        Open/ClosedOpen => Closed
    2015-10-12 ignat Attached File- => Added grub2.patch, #35169

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