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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id b19-20020a05620a271300b007659935ce64sm65524qkp.71.2023.11.16.12.15.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 12:15:52 -0800 (PST) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: peterx@redhat.com, Muhammad Usama Anjum , Andrew Morton , David Hildenbrand , Andrei Vagin , syzbot+7ca4b2719dc742b8d0a4@syzkaller.appspotmail.com Subject: [PATCH 2/3] mm/pagemap: Fix wr-protect even if PM_SCAN_WP_MATCHING not set Date: Thu, 16 Nov 2023 15:15:46 -0500 Message-ID: <20231116201547.536857-3-peterx@redhat.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231116201547.536857-1-peterx@redhat.com> References: <20231116201547.536857-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The new pagemap ioctl contains a fast path for wr-protections without looking into category masks. It forgets to check PM_SCAN_WP_MATCHING before applying the wr-protections. It can cause, e.g., pte markers installed on archs that do not even support uffd wr-protect. WARNING: CPU: 0 PID: 5059 at mm/memory.c:1520 zap_pte_range mm/memory.c:152= 0 [inline] Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS= _WRITTEN flag") Reported-by: syzbot+7ca4b2719dc742b8d0a4@syzkaller.appspotmail.com Signed-off-by: Peter Xu Reviewed-by: Andrei Vagin Reviewed-by: David Hildenbrand --- fs/proc/task_mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index e91085d79926..d19924bf0a39 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2171,7 +2171,7 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigne= d long start, return 0; } =20 - if (!p->vec_out) { + if ((p->arg.flags & PM_SCAN_WP_MATCHING) && !p->vec_out) { /* Fast path for performing exclusive WP */ for (addr =3D start; addr !=3D end; pte++, addr +=3D PAGE_SIZE) { if (pte_uffd_wp(ptep_get(pte))) --=20 2.41.0