patchlwIP - A Lightweight TCP/IP stack - Patches: patch #10121, bug: httpd creates circular linked...

 
 

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patch #10121: bug: httpd creates circular linked list that causes an infinite loop

Submitted by:  Peter Lawrence <majbthrd>
Submitted on:  Wed 13 Oct 2021 09:52:03 PM UTC
 
Category:  Contrib Priority:  6
Status:  None Privacy:  Public
Assigned to:  None Open/Closed:  Open
Planned Release:  None
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Wed 13 Oct 2021 09:52:03 PM UTC, original submission:  

This pertains to the httpd service in ./src/apps/http/httpd.c

Unless the user has specifically overridden the normally enabled LWIP_HTTPD_SUPPORT_REQUESTLIST, the right input sequence will cause httpd to go into an infinite loop.

To reproduce, telnet to the httpd service port and press the ENTER key twice.

What I observe is that this test procedure results in two calls to the httpd handler with the same pbuf pointer.  In the code below the comment "enqueue the pbuf", there is a call to pbuf_cat() to concatenate the existing pbuf to itself, and in the later pbuf_len() call will then proceed to count this circular linked list for the rest of time.

Peter Lawrence <majbthrd>

 

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Attached Files
file #52096:  httpd.diff added by majbthrd (483B - application/octet-stream)

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-10-13 majbthrd Attached File- => Added httpd.diff, #52096

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