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([2804:1b3:a7c0:c914:a525:210b:3f9e:9366]) by smtp.gmail.com with ESMTPSA id s132-20020acac28a000000b003926e3328e6sm606890oif.8.2023.05.18.05.58.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 May 2023 05:58:40 -0700 (PDT) Message-ID: Date: Thu, 18 May 2023 09:58:37 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH] setsourcefilter: Replace alloca with a scratch_buffer. Content-Language: en-US To: Joe Simmons-Talbott , libc-alpha@sourceware.org References: <20230516134549.1488655-1-josimmon@redhat.com> From: Adhemerval Zanella Netto Organization: Linaro In-Reply-To: <20230516134549.1488655-1-josimmon@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-13.3 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_SHORT,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 16/05/23 10:45, Joe Simmons-Talbott wrote: > Use a scratch_buffer rather than either alloca or malloc to reduce the > possibility of a stack overflow. > > Suggested-by: Adhemerval Zanella Netto LGTM, thanks. Reviewed-by: Adhemerval Zanella > --- > sysdeps/unix/sysv/linux/setsourcefilter.c | 27 ++++++----------------- > 1 file changed, 7 insertions(+), 20 deletions(-) > > diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c > index 538f4de696..479744f169 100644 > --- a/sysdeps/unix/sysv/linux/setsourcefilter.c > +++ b/sysdeps/unix/sysv/linux/setsourcefilter.c > @@ -16,13 +16,10 @@ > License along with the GNU C Library; if not, see > . */ > > -#include > #include > -#include > #include > -#include > #include > -#include > +#include > #include "getsourcefilter.h" > > > @@ -34,17 +31,12 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group, > /* We have to create an struct ip_msfilter object which we can pass > to the kernel. */ > size_t needed = GROUP_FILTER_SIZE (numsrc); > - int use_alloca = __libc_use_alloca (needed); > > - struct group_filter *gf; > - if (use_alloca) > - gf = (struct group_filter *) alloca (needed); > - else > - { > - gf = (struct group_filter *) malloc (needed); > - if (gf == NULL) > - return -1; > - } > + struct scratch_buffer buf; > + scratch_buffer_init (&buf); > + if (!scratch_buffer_set_array_size (&buf, 1, needed)) > + return -1; > + struct group_filter *gf = buf.data; > > gf->gf_interface = interface; > memcpy (&gf->gf_group, group, grouplen); > @@ -63,12 +55,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group, > else > result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed); > > - if (! use_alloca) > - { > - int save_errno = errno; > - free (gf); > - __set_errno (save_errno); > - } > + scratch_buffer_free (&buf); > > return result; > }