[{"id":3677171,"web_url":"http://patchwork.ozlabs.org/comment/3677171/","msgid":"<20260414124418.3792-1-linuxtestproject.agent@gmail.com>","list_archive_url":null,"date":"2026-04-14T12:44:18","subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","submitter":{"id":93132,"url":"http://patchwork.ozlabs.org/api/people/93132/","name":null,"email":"linuxtestproject.agent@gmail.com"},"content":"Hi Martin,\n\nour agent completed the review of the patch.\n\nThe agent can sometimes produce false positives although often its\nfindings are genuine. If you find issues with the review, please\ncomment this email or ignore the suggestions.\n\nOn Wed, 20 Jan 2038, Martin Cermak wrote:\n> Avoid syscall param ioctl(generic) points to uninitialised byte(s)\n\nThe subject is a raw Valgrind diagnostic string, not a commit subject.\nName the component and the fix, e.g.:\n userfaultfd01: initialize uffdio_register to avoid uninitialized bytes\n\n> lib/tst_clocks.c: fix uninitialized memory in run() Reproducible\n> using userfaultfd01.\n\nThe file named here (lib/tst_clocks.c) is not the file changed by this\npatch; the actual change is in\ntestcases/kernel/syscalls/userfaultfd/userfaultfd01.c. Please correct\nthis and explain why uffdio_register was uninitialized (the ioctls field\nis not set before UFFDIO_REGISTER is called).\n\nRegards,\nLTP AI Reviewer","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","ltp@lists.linux.it"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ltp@picard.linux.it"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=NaT4twji;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.linux.it\n (client-ip=213.254.12.146; helo=picard.linux.it;\n envelope-from=ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it;\n receiver=patchwork.ozlabs.org)"],"Received":["from picard.linux.it (picard.linux.it [213.254.12.146])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fw3rC3xgyz1xtJ\n\tfor ; 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charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it","Sender":"\"ltp\" "}},{"id":3677582,"web_url":"http://patchwork.ozlabs.org/comment/3677582/","msgid":"","list_archive_url":null,"date":"2026-04-15T10:18:20","subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","submitter":{"id":8530,"url":"http://patchwork.ozlabs.org/api/people/8530/","name":"Cyril Hrubis","email":"chrubis@suse.cz"},"content":"Hi!\n> From b81924101f441d7f2103197c8b81a38e8920fda4 Mon Sep 17 00:00:00 2001\n> From: Super User \n> Date: Wed, 20 Jan 2038 01:08:34 -0500\n> Subject: [PATCH] Avoid syscall param ioctl(generic) points to uninitialised\n> byte(s)\n> \n> lib/tst_clocks.c: fix uninitialized memory in run() Reproducible\n> using userfaultfd01.\n\nThis description does not seem to correspond to the actual change.\n\n> Signed-off-by: Martin Cermak \n> ---\n> testcases/kernel/syscalls/userfaultfd/userfaultfd01.c | 4 ++--\n> 1 file changed, 2 insertions(+), 2 deletions(-)\n> \n> diff --git a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> index 7368d3863..d24766e7c 100644\n> --- a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> +++ b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> @@ -92,8 +92,8 @@ static void *handle_thread(void)\n> static void run(unsigned int i)\n> {\n> \tpthread_t thr;\n> -\tstruct uffdio_api uffdio_api = {};\n> -\tstruct uffdio_register uffdio_register;\n> +\tstruct uffdio_api uffdio_api = {0, };\n> +\tstruct uffdio_register uffdio_register = {0, };\n\nGiven that we were using = {}; in the code before can we keep using that\nand for all instances?\n\nAlso I assume the problem is the ioctls field in the uffdio_api\nstructure that is not initialized beacuse is supposed to be set by\nkernel before returning into userspace. Should valgrind warn about such\ncases?","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","ltp@lists.linux.it"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ltp@picard.linux.it"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.linux.it\n (client-ip=2001:1418:10:5::2; helo=picard.linux.it;\n envelope-from=ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it;\n receiver=patchwork.ozlabs.org)","smtp-out2.suse.de;\n\tnone"],"Received":["from picard.linux.it (picard.linux.it [IPv6:2001:1418:10:5::2])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fwcY20rB8z1yDF\n\tfor ; Wed, 15 Apr 2026 20:18:14 +1000 (AEST)","from picard.linux.it (localhost [IPv6:::1])\n\tby picard.linux.it (Postfix) with ESMTP id 9AD1A3E5BAC\n\tfor ; Wed, 15 Apr 2026 12:18:11 +0200 (CEST)","from in-5.smtp.seeweb.it (in-5.smtp.seeweb.it [217.194.8.5])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature ECDSA (secp384r1))\n (No client certificate requested)\n by picard.linux.it (Postfix) with ESMTPS id 9E18C3C1E06\n for ; 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Wed, 15 Apr 2026 10:18:06 +0000"],"Date":"Wed, 15 Apr 2026 12:18:20 +0200","From":"Cyril Hrubis ","To":"Martin Cermak ","Message-ID":"","References":"<20260414114758.7xtei7hyddxu2fic@lida.tpb.lab.eng.brq.redhat.com>","MIME-Version":"1.0","Content-Disposition":"inline","In-Reply-To":"<20260414114758.7xtei7hyddxu2fic@lida.tpb.lab.eng.brq.redhat.com>","X-Rspamd-Pre-Result":["action=no action; module=replies;\n Message is reply to one we originated","action=no action; module=replies;\n Message is reply to one we originated"],"X-Rspamd-Queue-Id":"925205BE39","X-Rspamd-Action":"no action","X-Spam-Score":"-4.00","X-Spam-Level":"","X-Spamd-Result":"default: False [-4.00 / 50.00];\n\tREPLY(-4.00)[]","X-Rspamd-Server":"rspamd1.dmz-prg2.suse.org","X-Spam-Status":"No, score=0.0 required=7.0 tests=SPF_HELO_NONE,SPF_PASS\n shortcircuit=no autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on in-5.smtp.seeweb.it","X-Virus-Scanned":"clamav-milter 1.0.9 at in-5.smtp.seeweb.it","X-Virus-Status":"Clean","Subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","X-BeenThere":"ltp@lists.linux.it","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"Linux Test Project ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Cc":"valgrind-developers@lists.sourceforge.net, ltp@lists.linux.it","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it","Sender":"\"ltp\" "}},{"id":3678044,"web_url":"http://patchwork.ozlabs.org/comment/3678044/","msgid":"<20260416092131.kkbfd3cdi3tv7z7l@lida.tpb.lab.eng.brq.redhat.com>","list_archive_url":null,"date":"2026-04-16T09:21:31","subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","submitter":{"id":88822,"url":"http://patchwork.ozlabs.org/api/people/88822/","name":"Martin Cermak","email":"mcermak@redhat.com"},"content":"Hi Cyril,\n\nOn Wed 2026-04-15 12:18 , Cyril Hrubis wrote:\n> Hi!\n> > From b81924101f441d7f2103197c8b81a38e8920fda4 Mon Sep 17 00:00:00 2001\n> > From: Super User \n> > Date: Wed, 20 Jan 2038 01:08:34 -0500\n> > Subject: [PATCH] Avoid syscall param ioctl(generic) points to uninitialised\n> > byte(s)\n> > \n> > lib/tst_clocks.c: fix uninitialized memory in run() Reproducible\n> > using userfaultfd01.\n> \n> This description does not seem to correspond to the actual change.\n\nOh, right, this is a true mistake in my proposed patch. Sorry about that.\n\n> \n> > Signed-off-by: Martin Cermak \n> > ---\n> > testcases/kernel/syscalls/userfaultfd/userfaultfd01.c | 4 ++--\n> > 1 file changed, 2 insertions(+), 2 deletions(-)\n> > \n> > diff --git a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > index 7368d3863..d24766e7c 100644\n> > --- a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > +++ b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > @@ -92,8 +92,8 @@ static void *handle_thread(void)\n> > static void run(unsigned int i)\n> > {\n> > \tpthread_t thr;\n> > -\tstruct uffdio_api uffdio_api = {};\n> > -\tstruct uffdio_register uffdio_register;\n> > +\tstruct uffdio_api uffdio_api = {0, };\n> > +\tstruct uffdio_register uffdio_register = {0, };\n> \n> Given that we were using = {}; in the code before can we keep using that\n> and for all instances?\n\nI saw both initializers in the LTP source, see `$ grep -rIn '= {};'` and\n`$ grep -rIn '= { 0, };'`. The latter one is compliant with older standards.\nBut to keep the coding style within this file, I've updated the initializer.\n\n> Also I assume the problem is the ioctls field in the uffdio_api\n> structure that is not initialized beacuse is supposed to be set by\n> kernel before returning into userspace. Should valgrind warn about such\n> cases?\n\nYou are right that zeroing just this uffdio_register.ioctls = 0; is suffi-\ncient to to avoid the valgrind complaint. Zeroing whole the struct seems\nsyntactically more concise and also correct.\n\nHere is how Valgrind complains when uffdio_register.ioctls isn't zero inited:\n\nel10 x86_64 # echo $T\n/root/ltp/testcases/kernel/syscalls/userfaultfd/userfaultfd01\nel10 x86_64 # \nel10 x86_64 # \nel10 x86_64 # \nel10 x86_64 # $T\ntst_test.c:2059: TINFO: LTP version: 20260130\ntst_test.c:2062: TINFO: Tested kernel: 6.12.0-218.el10.x86_64 #1 SMP PREEMPT_DYNAMIC Tue Mar 31 08:07:36 EDT 2026 x86_64\ntst_kconfig.c:90: TINFO: Parsing kernel config '/lib/modules/6.12.0-218.el10.x86_64/build/.config'\ntst_test.c:1887: TINFO: Overall timeout per run is 0h 25m 00s\nuserfaultfd01.c:120: TPASS: Pagefault handled!\nuserfaultfd01.c:120: TPASS: Pagefault handled!\n\nSummary:\npassed 2\nfailed 0\nbroken 0\nskipped 0\nwarnings 0\nel10 x86_64 # valgrind $T\ntst_test.c:2059: TINFO: LTP version: 20260130\ntst_test.c:2062: TINFO: Tested kernel: 6.12.0-218.el10.x86_64 #1 SMP PREEMPT_DYNAMIC Tue Mar 31 08:07:36 EDT 2026 x86_64\ntst_kconfig.c:90: TINFO: Parsing kernel config '/lib/modules/6.12.0-218.el10.x86_64/build/.config'\ntst_test.c:1887: TINFO: Overall timeout per run is 0h 25m 00s\n==2747289== Syscall param ioctl(generic) points to uninitialised byte(s)\n==2747289== at 0x4966D1F: ioctl (ioctl.c:36)\n==2747289== by 0x40534C: run (userfaultfd01.c:113)\n==2747289== by 0x41164C: run_tests (tst_test.c:1730)\n==2747289== by 0x41164C: testrun (tst_test.c:1796)\n==2747289== by 0x41164C: fork_testrun (tst_test.c:1936)\n==2747289== by 0x413B74: tst_run_tcases (tst_test.c:2079)\n==2747289== by 0x404E8D: main (tst_test.h:755)\n==2747289== Address 0x1ffefff98a is on thread 1's stack\n==2747289== in frame #1, created by run (userfaultfd01.c:93)\n==2747289== \n==2747289== \n==2747289== Exit program on first error (--exit-on-first-error=yes)\ntst_test.c:1953: TBROK: Child returned with 253\n\nSummary:\npassed 0\nfailed 0\nbroken 1\nskipped 0\nwarnings 0\nel10 x86_64 # \n\n\nHere is the updated patch (inline):\n\n\n---------------------------------8<------------------------------------\n$ cat 0001-userfaultfd01.c-Zero-initialize-the-uffdio_register-.patch \nFrom e1ed7e74551bfa51204e1f45fe0b3bb64f21bcae Mon Sep 17 00:00:00 2001\nFrom: Martin Cermak \nDate: Thu, 16 Apr 2026 11:15:38 +0200\nSubject: [PATCH] userfaultfd01.c: Zero-initialize the uffdio_register struct\n\nWithout this patch, valgrind complains when running userfaultfd01:\n\nel10 x86_64 # valgrind testcases/kernel/syscalls/userfaultfd/userfaultfd01\ntst_test.c:2059: TINFO: LTP version: 20260130\ntst_test.c:2062: TINFO: Tested kernel: 6.12.0-218.el10.x86_64 #1 SMP PREEMPT_DYNAMIC Tue Mar 31 08:07:36 EDT 2026 x86_64\ntst_kconfig.c:90: TINFO: Parsing kernel config '/lib/modules/6.12.0-218.el10.x86_64/build/.config'\ntst_test.c:1887: TINFO: Overall timeout per run is 0h 25m 00s\n==2748329== Syscall param ioctl(generic) points to uninitialised byte(s)\n==2748329== at 0x4966D1F: ioctl (ioctl.c:36)\n==2748329== by 0x40534C: run (userfaultfd01.c:113)\n==2748329== by 0x41164C: run_tests (tst_test.c:1730)\n==2748329== by 0x41164C: testrun (tst_test.c:1796)\n==2748329== by 0x41164C: fork_testrun (tst_test.c:1936)\n==2748329== by 0x413B74: tst_run_tcases (tst_test.c:2079)\n==2748329== by 0x404E8D: main (tst_test.h:755)\n==2748329== Address 0x1ffefff98a is on thread 1's stack\n==2748329== in frame #1, created by run (userfaultfd01.c:93)\n==2748329==\n==2748329==\n==2748329== Exit program on first error (--exit-on-first-error=yes)\ntst_test.c:1953: TBROK: Child returned with 253\n\nIt would be sufficient to zero out the uffdio_register.ioctls member.\nThis patch inits whole the struct before use.\n---\n testcases/kernel/syscalls/userfaultfd/userfaultfd01.c | 2 +-\n 1 file changed, 1 insertion(+), 1 deletion(-)\n\ndiff --git a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\nindex 7368d3863..bd955ffdd 100644\n--- a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n+++ b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n@@ -93,7 +93,7 @@ static void run(unsigned int i)\n {\n pthread_t thr;\n struct uffdio_api uffdio_api = {};\n- struct uffdio_register uffdio_register;\n+ struct uffdio_register uffdio_register {};\n struct tcase *tc = &tcases[i];\n \n if (tc->kver == AFTER_5_11 && kver == BEFORE_5_11)","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","ltp@lists.linux.it"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ltp@picard.linux.it"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=lists.linux.it header.i=@lists.linux.it\n header.a=rsa-sha256 header.s=picard header.b=iTLIKX2M;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 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autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on in-2.smtp.seeweb.it","X-Virus-Scanned":"clamav-milter 1.0.9 at in-2.smtp.seeweb.it","X-Virus-Status":"Clean","Subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","X-BeenThere":"ltp@lists.linux.it","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"Linux Test Project ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","From":"Martin Cermak via ltp ","Reply-To":"Martin Cermak ","Cc":"valgrind-developers@lists.sourceforge.net, ltp@lists.linux.it","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it","Sender":"\"ltp\" "}},{"id":3678070,"web_url":"http://patchwork.ozlabs.org/comment/3678070/","msgid":"","list_archive_url":null,"date":"2026-04-16T10:07:18","subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","submitter":{"id":8530,"url":"http://patchwork.ozlabs.org/api/people/8530/","name":"Cyril Hrubis","email":"chrubis@suse.cz"},"content":"Hi!\n> > > diff --git a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > index 7368d3863..d24766e7c 100644\n> > > --- a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > +++ b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > @@ -92,8 +92,8 @@ static void *handle_thread(void)\n> > > static void run(unsigned int i)\n> > > {\n> > > \tpthread_t thr;\n> > > -\tstruct uffdio_api uffdio_api = {};\n> > > -\tstruct uffdio_register uffdio_register;\n> > > +\tstruct uffdio_api uffdio_api = {0, };\n> > > +\tstruct uffdio_register uffdio_register = {0, };\n> > \n> > Given that we were using = {}; in the code before can we keep using that\n> > and for all instances?\n> \n> I saw both initializers in the LTP source, see `$ grep -rIn '= {};'` and\n> `$ grep -rIn '= { 0, };'`. The latter one is compliant with older standards.\n> But to keep the coding style within this file, I've updated the initializer.\n> \n> > Also I assume the problem is the ioctls field in the uffdio_api\n> > structure that is not initialized beacuse is supposed to be set by\n> > kernel before returning into userspace. Should valgrind warn about such\n> > cases?\n> \n> You are right that zeroing just this uffdio_register.ioctls = 0; is suffi-\n> cient to to avoid the valgrind complaint. Zeroing whole the struct seems\n> syntactically more concise and also correct.\n\nThat's not what I was trying to point out. Some fields of structures\npassed to ioctls are output-only. The question is if valgrind should\nwarn if we do not set output only field in such structure?","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","ltp@lists.linux.it"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ltp@picard.linux.it"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n unprotected) header.d=suse.cz header.i=@suse.cz header.a=rsa-sha256\n header.s=susede2_rsa header.b=u+KNim2e;\n\tdkim=fail reason=\"signature verification failed\" header.d=suse.cz\n header.i=@suse.cz header.a=ed25519-sha256 header.s=susede2_ed25519\n header.b=PSq3BnSc;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key)\n header.d=suse.cz header.i=@suse.cz header.a=rsa-sha256 header.s=susede2_rsa\n header.b=u+KNim2e;\n\tdkim=neutral header.d=suse.cz header.i=@suse.cz header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=PSq3BnSc;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.linux.it\n (client-ip=213.254.12.146; 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charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it","Sender":"\"ltp\" "}},{"id":3678148,"web_url":"http://patchwork.ozlabs.org/comment/3678148/","msgid":"<20260416123923.3xxfhyxztcw2rqth@lida.tpb.lab.eng.brq.redhat.com>","list_archive_url":null,"date":"2026-04-16T12:39:23","subject":"Re: [LTP] Avoid syscall param ioctl(generic) points to\n uninitialised byte(s)","submitter":{"id":88822,"url":"http://patchwork.ozlabs.org/api/people/88822/","name":"Martin Cermak","email":"mcermak@redhat.com"},"content":"On Thu 2026-04-16 12:07 , Cyril Hrubis wrote:\n> Hi!\n> > > > diff --git a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > > index 7368d3863..d24766e7c 100644\n> > > > --- a/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > > +++ b/testcases/kernel/syscalls/userfaultfd/userfaultfd01.c\n> > > > @@ -92,8 +92,8 @@ static void *handle_thread(void)\n> > > > static void run(unsigned int i)\n> > > > {\n> > > > \tpthread_t thr;\n> > > > -\tstruct uffdio_api uffdio_api = {};\n> > > > -\tstruct uffdio_register uffdio_register;\n> > > > +\tstruct uffdio_api uffdio_api = {0, };\n> > > > +\tstruct uffdio_register uffdio_register = {0, };\n> > > \n> > > Given that we were using = {}; in the code before can we keep using that\n> > > and for all instances?\n> > \n> > I saw both initializers in the LTP source, see `$ grep -rIn '= {};'` and\n> > `$ grep -rIn '= { 0, };'`. The latter one is compliant with older standards.\n> > But to keep the coding style within this file, I've updated the initializer.\n> > \n> > > Also I assume the problem is the ioctls field in the uffdio_api\n> > > structure that is not initialized beacuse is supposed to be set by\n> > > kernel before returning into userspace. Should valgrind warn about such\n> > > cases?\n> > \n> > You are right that zeroing just this uffdio_register.ioctls = 0; is suffi-\n> > cient to to avoid the valgrind complaint. Zeroing whole the struct seems\n> > syntactically more concise and also correct.\n> \n> That's not what I was trying to point out. Some fields of structures\n> passed to ioctls are output-only. The question is if valgrind should\n> warn if we do not set output only field in such structure?\n\nYou are very right. Curent version of valgrind doesn't recognize\nUFFDIO_REGISTER, and treats this ioctl as unknown ioctl via\nML_(PRE_unknown_ioctl)(tid, ARG2, ARG3); Good point, thanks!\n\nMartin","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","ltp@lists.linux.it"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ltp@picard.linux.it"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=lists.linux.it header.i=@lists.linux.it\n header.a=rsa-sha256 header.s=picard header.b=f/yzS4Fj;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=dEtE7Gcd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.linux.it\n (client-ip=213.254.12.146; helo=picard.linux.it;\n envelope-from=ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it;\n receiver=patchwork.ozlabs.org)"],"Received":["from picard.linux.it (picard.linux.it [213.254.12.146])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fxHdk4w7Wz1yCv\n\tfor ; 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