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Date:      Mon, 21 May 2001 15:59:15 +0200
From:      Thierry.Herbelot@alcatel.fr
To:        hackers@freebsd.org, Audit@freebsd.org
Subject:   memory leak in libfetch ? (with patch)
Message-ID:  <C1256A53.004CE34F.00@frmta003.netfr.alcatel.fr>

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hello,

[this is using a 4.3-Release machine]

I'm using libfetch for automated file transfers from a program (via ftp).

The program is running for long periods of time, and seems to be leaking memory (at least it's SIZE in top(1) just grows and grows - the swap is also increasingly used).

As there is no dynamically allocated memory in my program, one suspect could be libfetch(3).

Indeed, there are 5 calls to malloc(3) in the source code of the lib :
- in common.c, line 263, which should not cause a leak as the pointer is stored in buf, which is later saved,
- in common.c, line 362, in a function which is not used in my app (the file name is known)
- in fetch.c, line 377, in a function which is used only for http/https transfers, thus not in my app,
- in http.c, line 517, in a function which is used only for http/https transfers, thus not in my app,
- finally in ftp.c, line 434, in a suspicious manner : the "io" variable is located on the stack, thus visible only from this function, gets a pointer to a newly allocated ftpio struct and disappears after _ftp_setup() returns.

The comparison between usr.bin/compress/zopen.c:zclose() and lib/libfetch/ftp.c:_ftp_close() shows a missing free(cookie) at the end of the function.

the following patch seems to cure the memory leak :
-----------------------------------------
--- ftp.c.ori  Sat Apr  7 19:30:48 2001
+++ ftp.c Mon May 21 15:26:42 2001
@@ -422,7 +422,9 @@
     io->err = 0;
     close(io->csd);
     io->csd = -1;
-    return io->err ? -1 : 0;
+    r = io->err ? -1 : 0;
+    free(io);
+    return (r);
 }

 static FILE *
-----------------------------------------

     TfH



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