From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.1 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: from second.openwall.net (second.openwall.net [193.110.157.125]) by inbox.vuxu.org (Postfix) with SMTP id 80C4D24722 for ; Sat, 22 Jun 2024 03:05:53 +0200 (CEST) Received: (qmail 26065 invoked by uid 550); 22 Jun 2024 01:05:45 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 26016 invoked from network); 22 Jun 2024 01:05:44 -0000 Date: Fri, 21 Jun 2024 21:06:01 -0400 From: Rich Felker To: Florian Ziesche Cc: musl@lists.openwall.com Message-ID: <20240622010600.GC10433@brightrain.aerifal.cx> References: <20240523202803.GC10433@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="NMuMz9nt05w80d4+" Content-Disposition: inline In-Reply-To: <20240523202803.GC10433@brightrain.aerifal.cx> User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] [PATCH] dynlink: fix get_lfs64() with posix_fallocate64 --NMuMz9nt05w80d4+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, May 23, 2024 at 04:28:03PM -0400, Rich Felker wrote: > On Fri, May 10, 2024 at 06:01:58PM +0200, Florian Ziesche wrote: > > Hi, > > > > this patch increases the buffer size by one in get_lfs64() so that it > > works with posix_fallocate64. > > "posix_fallocate64" is 17 characters long, so 16 is one too short. > > > > Simplified example: > > before: https://compiler-explorer.com/z/4qcPhcaWr > > after: https://compiler-explorer.com/z/scGvhddKW > > > > --- > > diff --git a/ldso/dynlink.c b/ldso/dynlink.c > > index 42687da2..8707ae1c 100644 > > --- a/ldso/dynlink.c > > +++ b/ldso/dynlink.c > > @@ -363,7 +363,7 @@ static struct symdef get_lfs64(const char *name) > > "stat\0statfs\0statvfs\0tmpfile\0truncate\0versionsort\0" > > "__fxstat\0__fxstatat\0__lxstat\0__xstat\0"; > > size_t l; > > - char buf[16]; > > + char buf[17]; > > for (l=0; name[l]; l++) { > > if (l >= sizeof buf) goto nomatch; > > buf[l] = name[l]; > > Thanks for catching this. I questioned whether the 17 is sufficient, > but indeed the buffer is never nul terminated except when removing the > 64, so it should be ok. > > I think I'll apply your patch as a direct fix, but the whole copying > operation is unnecessary and I'll probably remove it. It works just as > well to strncmp and pass p instead of buf to find_sym, so that a > mutable copy of the name to lookup is never needed. Applied. Does the attached look ok to get rid of the copy entirely? It passed basic smoke testing here. --NMuMz9nt05w80d4+ Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="get_lfs64.diff" diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 8707ae1c..3b57c07f 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -362,19 +362,14 @@ static struct symdef get_lfs64(const char *name) "pwritev\0readdir\0scandir\0sendfile\0setrlimit\0" "stat\0statfs\0statvfs\0tmpfile\0truncate\0versionsort\0" "__fxstat\0__fxstatat\0__lxstat\0__xstat\0"; - size_t l; - char buf[17]; - for (l=0; name[l]; l++) { - if (l >= sizeof buf) goto nomatch; - buf[l] = name[l]; - } if (!strcmp(name, "readdir64_r")) return find_sym(&ldso, "readdir_r", 1); - if (l<2 || name[l-2]!='6' || name[l-1]!='4') + size_t l = strnlen(name, 18); + if (l<2 || name[l-2]!='6' || name[l-1]!='4' || name[l]) goto nomatch; - buf[l-=2] = 0; for (p=lfs64_list; *p; p++) { - if (!strcmp(buf, p)) return find_sym(&ldso, buf, 1); + if (!strncmp(name, p, l-2) && !p[l-2]) + return find_sym(&ldso, p, 1); while (*p) p++; } nomatch: --NMuMz9nt05w80d4+--