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Re: [patch] libcurl 7.12.2-20040917 and CURLOPT_VERBOSE may read free()ed data

From: Daniel Stenberg <daniel-curl_at_haxx.se>
Date: Wed, 22 Sep 2004 14:30:23 +0200 (CEST)

On Tue, 21 Sep 2004, Bertrand Demiddelaer wrote:

> I'm using licurl-7.12.2-20040917 on a monoprocess/monothread application
> with curl_multi et curl_share interfaces (for dns). I noticed that enabling
> CURLOPT_VERBOSE could cause this kind of report with valgrind:
>
> ==29530== Invalid read of size 4
> ==29530== at 0x807F1A4: Curl_printable_address (hostip.c:191)
> ==29530== by 0x8083CD4: verboseconnect (url.c:2001)
> ==29530== by 0x8085AFB: SetupConnection (url.c:3383)
>
> Here's a patch which seems to solve this problem for me. All curl tests
> passed, except for test 506. I guess the failure of this test is triggered
> by the calls to Curl_share_lock() and Curl_share_unlock() I added around a
> "lonely" dns->inuse++ (these new calls were not needed to solve my problem,
> but I guess they were missing. May be I'm wrong).

Thanks for your work.

Can you please enlighten me on what situation that causes this problem? Your
fix seems to make the second call to the verboseconnect() function use the
previous result. When is it calling this twice on the same connection? Or
rather, why is the conn->ip_addr pointer not a fine pointer anymore? It is
supposed to point to a addrinfo struct which shouldn't be free()d until the
connection is closed.

Or have I just had too little coffe?

-- 
      Daniel Stenberg -- http://curl.haxx.se -- http://daniel.haxx.se
       Dedicated custom curl help for hire: http://haxx.se/curl.html
Received on 2004-09-22

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