Date: Mon, 16 Nov 2009 21:12:47 +0100 From: volker@vwsoft.com To: Jim Wilcoxson <prirun@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: acl_from_text leaking memory Message-ID: <4B01B23F.8040002@vwsoft.com> In-Reply-To: <c5830b750911150847r3698b21ey819d4de3312ef78d@mail.gmail.com> References: <c5830b750911150804i694b00aai891819242816e89c@mail.gmail.com> <c5830b750911150847r3698b21ey819d4de3312ef78d@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 01/-10/63 20:59, Jim Wilcoxson wrote:
> I've been working on a new backup program, HashBackup, and believe I
> have found a memory leak with ACLs in PCBSD/FreeBSD 7.1 and OSX
> (Leopard).
>
> acl_from_text is a function that takes a text string as input, and
> returns a pointer to a malloc'd acl. This acl is then freed with
> acl_free. I noticed that acl_from_text appears to leak memory. This
> is not used during the backup of a filesystem, but is needed to do a
> restore.
>
> After looking at the acl_from_text source in /usr/src/lib/libc/posix1e
> (from PCBSD7.1), I believe the problem is that the duplicate text
> string, mybuf_p, is not freed on normal return of this function. Here
> is the end of this function:
>
> }
>
> #if 0
> /* XXX Should we only return ACLs valid according to acl_valid? */
> /* Verify validity of the ACL we read in. */
> if (acl_valid(acl) == -1) {
> errno = EINVAL;
> goto error_label;
> }
> #endif
>
> return(acl);
>
> error_label:
> acl_free(acl);
> free(mybuf_p);
> return(NULL);
> }
>
> I think there should be a free(mybuf_p) before return(acl).
>
> Here is a PCBSD/FreeBSD test program that causes the memory leak:
>
> #include <stdio.h>
> #include <sys/types.h>
> #include <sys/acl.h>
>
> main() {
> acl_t acl;
> char* acltext;
>
> acltext = "user::rw-\n group::r--\n mask::r--\n other::r--\n";
> while (1) {
> acl = acl_from_text(acltext);
> if (acl == NULL)
> printf("acl_from_text failed\n");
> if (acl_free(acl) != 0)
> printf("acl_free failed\n");
> }
> }
>
> I've subscribed to the lists for a few days in case there are
> questions or I can help test something.
>
> Thanks,
> Jim
> --
> HashBackup beta: http://sites.google.com/site/hashbackup
>
Jim,
you may want to have a look at the manpage acl_from_text(3):
"...This function may cause memory to be allocated. The caller should
free any releasable memory, when the new ACL is no longer required, by
calling acl_free(3) with the (void *)acl_t as an argument."
Please use an acl_free(void *obj_p) call afterwards to avoid leaking memory.
Volker
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4B01B23F.8040002>