linux-kernel - Re: [PATCH] perf/genelf: Switch deprecated openssl MD5

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Date:   Tue, 6 Sep 2022 09:33:35 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Zixuan Tan <tanzixuan.me@...il.com>
Cc:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/genelf: Switch deprecated openssl MD5_* functions
 to new EVP API

Em Tue, Sep 06, 2022 at 05:40:24PM +0800, Zixuan Tan escreveu:
> Hi Arnaldo, are there any updates?

Trying to apply it manually:

⬢[acme@...lbox perf-urgent]$ am
Applying: perf/genelf: Switch deprecated openssl MD5_* functions to new EVP API
error: corrupt patch at line 31
Patch failed at 0001 perf/genelf: Switch deprecated openssl MD5_* functions to new EVP API
hint: Use 'git am --show-current-patch=diff' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
⬢[acme@...lbox perf-urgent]$ git am --abort
⬢[acme@...lbox perf-urgent]$
⬢[acme@...lbox perf-urgent]$ patch -p1 < ~/wb/1.patch
patching file tools/perf/util/genelf.c
patch: **** malformed patch at line 141: const void *code, size_t csize)

⬢[acme@...lbox perf-urgent]$

⬢[acme@...lbox perf-urgent]$ tail -30  ~/wb/1.patch
 #endif
@@ -142,15 +139,20 @@ gen_build_id(struct buildid_note *note,
 static void
 gen_build_id(struct buildid_note *note, unsigned long load_addr,
const void *code, size_t csize)
 {
-       MD5_CTX context;
+       EVP_MD_CTX *mdctx;

        if (sizeof(note->build_id) < 16)
                errx(1, "build_id too small for MD5");

-       MD5_Init(&context);
-       MD5_Update(&context, &load_addr, sizeof(load_addr));
-       MD5_Update(&context, code, csize);
-       MD5_Final((unsigned char *)note->build_id, &context);
+       mdctx = EVP_MD_CTX_new();
+       if (!mdctx)
+               errx(2, "failed to create EVP_MD_CTX");
+
+       EVP_DigestInit_ex(mdctx, EVP_md5(), NULL);
+       EVP_DigestUpdate(mdctx, &load_addr, sizeof(load_addr));
+       EVP_DigestUpdate(mdctx, code, csize);
+       EVP_DigestFinal_ex(mdctx, (unsigned char *)note->build_id, NULL);
+       EVP_MD_CTX_free(mdctx);
 }
 #endif

--
2.34.1
⬢[acme@...lbox perf-urgent]$
 
> Thanks,
> - Zixuan
> 
> On Sat, Aug 27, 2022 at 2:32 AM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > Hello,
> >
> > On Fri, Aug 26, 2022 at 10:22 AM Zixuan Tan <tanzixuan.me@...il.com> wrote:
> > >
> > > On Fri, Aug 26, 2022 at 4:17 AM Arnaldo Carvalho de Melo
> > > <arnaldo.melo@...il.com> wrote:
> > > >
> > > > Em Fri, Aug 26, 2022 at 01:00:58AM +0800, Zixuan Tan escreveu:
> > > > > Switch to the flavored EVP API like in test-libcrypto.c, and remove the
> > > > > bad gcc #pragma.
> > > > >
> > > > > Inspired-By: 5b245985a6de ("tools build: Switch to new openssl API for
> > > > > test-libcrypto")
> > > >
> > > > How did you test the end result? Can you please describe step by step?
> > > >
> > > > Also please consider adding a 'perf test' entry to make sure this
> > > > doesn't regress.
> > >
> > > Sorry but I don't get what you mean, what results do I need to test?
> > >
> > > These EVP_* APIs are just replacements for the deprecated MD5_* APIs in
> > > openssl v3 [1][2]. With the same input, they produce the same MD5 digest.
> > >
> > > And this patch just does the migration work for the upgrade and does not
> > > change the logic of the code. so...what should I test?
> >
> > Yeah, I understand that this merely changes the MD5 APIs.
> > While it's good to have a test case for the genelf code, I don't think
> > it belongs to this patch.  So,
> >
> > Acked-by: Namhyung Kim <namhyung@...nel.org>
> >
> >
> > >
> > > Links:
> > > [1] https://www.openssl.org/docs/man3.0/man3/MD5.html
> > > [2] https://stackoverflow.com/questions/69806220/advice-needed-for-migration-of-low-level-openssl-api-to-high-level-openssl-apis

-- 

- Arnaldo