Re: [PATCH v3] Fix leak in getaddrinfo introduced by the fix for CVE-2023-4806 [BZ #30843]

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 2023-09-25 01:18, Romain Geissler wrote:
> Changes since v2:
>   - Format Makefile so that lines do not exceed 79 chars.
>   - Add a space " " between "mtrace" and "()" in the test, as it seems
>     it's the coding style used elsewhere in glibc.
> 
> 
> Fix leak in getaddrinfo introduced by the fix for CVE-2023-4806 [BZ#30843]

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

> 
> ---
>   nss/Makefile                    | 20 ++++++++++++++++++++
>   nss/tst-nss-gai-hv2-canonname.c |  3 +++
>   sysdeps/posix/getaddrinfo.c     |  4 +---
>   3 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/nss/Makefile b/nss/Makefile
> index e3d21e9a899..6ef5bf23b30 100644
> --- a/nss/Makefile
> +++ b/nss/Makefile
> @@ -148,6 +148,15 @@ endif
>   extra-test-objs		+= nss_test1.os nss_test2.os nss_test_errno.os \
>   			   nss_test_gai_hv2_canonname.os
>   
> +ifeq ($(run-built-tests),yes)
> +ifneq (no,$(PERL))
> +tests-special += $(objpfx)mtrace-tst-nss-gai-hv2-canonname.out
> +endif
> +endif
> +
> +generated += mtrace-tst-nss-gai-hv2-canonname.out \
> +		tst-nss-gai-hv2-canonname.mtrace
> +
>   include ../Rules
>   
>   ifeq (yes,$(have-selinux))
> @@ -216,6 +225,17 @@ endif
>   $(objpfx)tst-nss-files-alias-leak.out: $(objpfx)/libnss_files.so
>   $(objpfx)tst-nss-files-alias-truncated.out: $(objpfx)/libnss_files.so
>   
> +tst-nss-gai-hv2-canonname-ENV = \
> +		MALLOC_TRACE=$(objpfx)tst-nss-gai-hv2-canonname.mtrace \
> +		LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
> +$(objpfx)mtrace-tst-nss-gai-hv2-canonname.out: \
> +  $(objpfx)tst-nss-gai-hv2-canonname.out
> +	{ test -r $(objpfx)tst-nss-gai-hv2-canonname.mtrace \
> +	|| ( echo "tst-nss-gai-hv2-canonname.mtrace does not exist"; exit 77; ) \
> +	&& $(common-objpfx)malloc/mtrace \
> +	$(objpfx)tst-nss-gai-hv2-canonname.mtrace; } > $@; \
> +	$(evaluate-test)
> +
>   # Disable DT_RUNPATH on NSS tests so that the glibc internal NSS
>   # functions can load testing NSS modules via DT_RPATH.
>   LDFLAGS-tst-nss-test1 = -Wl,--disable-new-dtags
> diff --git a/nss/tst-nss-gai-hv2-canonname.c b/nss/tst-nss-gai-hv2-canonname.c
> index d5f10c07d6a..7db53cf09da 100644
> --- a/nss/tst-nss-gai-hv2-canonname.c
> +++ b/nss/tst-nss-gai-hv2-canonname.c
> @@ -21,6 +21,7 @@
>   #include <netdb.h>
>   #include <stdlib.h>
>   #include <string.h>
> +#include <mcheck.h>
>   #include <support/check.h>
>   #include <support/xstdio.h>
>   #include "nss/tst-nss-gai-hv2-canonname.h"
> @@ -41,6 +42,8 @@ static void do_prepare (int a, char **av)
>   static int
>   do_test (void)
>   {
> +  mtrace ();
> +
>     __nss_configure_lookup ("hosts", "test_gai_hv2_canonname");
>   
>     struct addrinfo hints = {};
> diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
> index b4e8ea3880a..69f38bbfb9e 100644
> --- a/sysdeps/posix/getaddrinfo.c
> +++ b/sysdeps/posix/getaddrinfo.c
> @@ -1196,9 +1196,7 @@ free_and_return:
>     if (malloc_name)
>       free ((char *) name);
>     free (addrmem);
> -  if (res.free_at)
> -    free (res.at);
> -  free (res.canon);
> +  gaih_result_reset (&res);
>   
>     return result;
>   }