Re: [PATCH] greybus: operation: fix out-of-bounds write in message allocation

[Johan Hovold]

On Tue, Sep 01, 2026 at 11:30:16PM -0400, Adriano Cordova wrote:
> The incoming message size from the device header (header.size) is
> trusted without checking that it is at least the size of the message
> header itself, but a value smaller than sizeof(struct gb_operation_msg_hdr)
> underflows request_size in gb_operation_create_incoming(), wraps around
> in gb_operation_message_alloc(), and results in a tiny buffer that is
> then written past its end in gb_operation_message_init().
> 
> Reject undersized messages before parsing the message header.
> 
> Fixes: d37b1db13f8b ("greybus: refactor gb_connection_recv()")

This isn't the commit that introduced the issue (even if that commit
made things worse by removing a WARN_ON()).

> Reported-by: syzbot+2fd6aefc361af86911d5@xxxxxxxxxxxxxxxxxxxxxxxxx
> Link: https://syzkaller.appspot.com/bug?extid=2fd6aefc361af86911d5
> Cc: stable@xxxxxxxxxxxxxxx

How did you find and fix this issue? Are you missing an Assisted-by tag
here?

> Signed-off-by: Adriano Cordova <adrianox@xxxxxxxxx>

Note that this is also being fixed here:

	https://lore.kernel.org/lkml/tencent_1CB189506DEFA4B38099D654FE6C2A2F2E07@xxxxxx/

Johan