From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A751C87FCB for ; Wed, 30 Jul 2025 17:07:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 99DA06B007B; Wed, 30 Jul 2025 13:07:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 94C5D6B0088; Wed, 30 Jul 2025 13:07:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8359B6B0089; Wed, 30 Jul 2025 13:07:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 6D7716B007B for ; Wed, 30 Jul 2025 13:07:40 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 1CCCA80732 for ; Wed, 30 Jul 2025 17:07:40 +0000 (UTC) X-FDA: 83721562680.25.3E61449 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) by imf13.hostedemail.com (Postfix) with ESMTP id 15BEC20011 for ; Wed, 30 Jul 2025 17:07:37 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=ldvCEMFp; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf13.hostedemail.com: domain of 3WFGKaAYKCG8fheRaOTbbTYR.PbZYVahk-ZZXiNPX.beT@flex--surenb.bounces.google.com designates 209.85.215.202 as permitted sender) smtp.mailfrom=3WFGKaAYKCG8fheRaOTbbTYR.PbZYVahk-ZZXiNPX.beT@flex--surenb.bounces.google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1753895258; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding:in-reply-to: references:dkim-signature; bh=iwvX/+FCFrBIkeHTGaFzh+izLhsSIPbGbCbxZr6W88I=; b=C+FVo1Sqz65w6WqpcgILhcYqGAYCBZf0H8bQjRAVSimKK1kyK+XGgrWWuEzw9JbHrxoiKw trAXoHIzZjqi3KizJz7l3+m5Klk75H+/FPoeYDUp1XN0rMsr9njl1FuzOwbHk2KPUalpq+ isUvtKXXzyK93VHnU73sZWaB66bFKZs= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1753895258; a=rsa-sha256; cv=none; b=u1rFhFgsdV4B6n2yMTyy3uN90zB7kyKCEZA95fx4w7T4iigpddLLDiYYxgv/7TSkfmmmHX 2gqD304XSfu35fKsHwNSSUmsH4newQnysmHqKOAUmww9bo5aXQteXT8M4xnzW9dTLUO14W SJDFF4rBNn+1iTSTZ0oIowSmvl3nwto= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=ldvCEMFp; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf13.hostedemail.com: domain of 3WFGKaAYKCG8fheRaOTbbTYR.PbZYVahk-ZZXiNPX.beT@flex--surenb.bounces.google.com designates 209.85.215.202 as permitted sender) smtp.mailfrom=3WFGKaAYKCG8fheRaOTbbTYR.PbZYVahk-ZZXiNPX.beT@flex--surenb.bounces.google.com Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b34fa832869so952850a12.1 for ; Wed, 30 Jul 2025 10:07:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1753895257; x=1754500057; darn=kvack.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=iwvX/+FCFrBIkeHTGaFzh+izLhsSIPbGbCbxZr6W88I=; b=ldvCEMFpAS7lK7BQIwKmcKA2AQOn2kIBRF5Y8TbRhUBE7cLRNSMFHBTexU39JLEvDR Uwth5cc/Brp41WaP92u+cZm2Kn6b+oVaMByn69vgPae7iE44rSgNmp/iO1PXPNHZtvxB KFdgEOAptcN1S47YfLgz/Ny1zDiuVQgBocXTXZ0lDZ/EnzxF16pFZdJNWnjPz9dKthR/ mPngnbaHhyg++lwOUNVGvZnuTLVG6xY2R/qmI6kP4gn1W3mryDYxlGwZerbjy5ZGV5GV oRsOx1cfdF43h9fZOO5mH6MlC1/S65Mcx9cgV5KIHZWu3hfxZS7tbkZXpImA0vPcFXPU pvtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753895257; x=1754500057; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=iwvX/+FCFrBIkeHTGaFzh+izLhsSIPbGbCbxZr6W88I=; b=NqWRq2u5yTir6aMNKl4020ihJ8hlskLx/7imAEm2+RZQLmGzkUsIlHRCSoEXJKw0hI rY+0IJNot1hEuD/EkOCrZLN3lytQPeyMwzKnd6Pko+2xRzrY9HzZY0pBw4mnTyNZjgcf 3w5wwvtGKaNZbmrzRO0PmfsZh5ePsK70tSIpUdgTpbmfm7SCFs6fncMfBVtPRP486o3z EJN//Ks7hoVYKHJsDahW6IZV1KovKzZ1pPNV76wmSF7FA15fiTfplNYBXaDSS00QLVp8 UNtulL7wlgr/kZ4QnjHU6pJ5zMj3C5ed9OrbmHrwmOxc/ufWGLCAW+DKvzvG6qg/yZ0x /qiQ== X-Forwarded-Encrypted: i=1; AJvYcCWzlSkqXgQQPa9h40JTse1w4FbGtNj8Xb4xm16VXcOLLLL3aEjHNfc2N7J0HTvPnHMB+OO1k08oWg==@kvack.org X-Gm-Message-State: AOJu0Yzr3lvCh/5wS3f3zQUKwUqJYe6Zb+6Zoe29akXfkEps7Qe7uy5R wubCS23Yn8QMyeypNnq/B9TxEGLcI5f4eP3RoJy4g74UcgaJNbWl1tqwSsCyKZDdg7bO5M4nWQs KaYngxQ== X-Google-Smtp-Source: AGHT+IFRpqzleLfhY584F3gS5nWpI1NhhfzwuIDnKy5qdpfvKqCIZN9aFroMt2PQhlQ+ZIOuvhwlGyX2lGc= X-Received: from pjee12.prod.google.com ([2002:a17:90b:578c:b0:313:246f:8d54]) (user=surenb job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:f54c:b0:240:b884:2fa0 with SMTP id d9443c01a7336-240b8843050mr21999235ad.26.1753895256448; Wed, 30 Jul 2025 10:07:36 -0700 (PDT) Date: Wed, 30 Jul 2025 10:07:33 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.50.1.552.g942d659e1b-goog Message-ID: <20250730170733.3829267-1-surenb@google.com> Subject: [PATCH 1/1] userfaultfd: fix a crash when UFFDIO_MOVE handles a THP hole From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: peterx@redhat.com, david@redhat.com, aarcange@redhat.com, lokeshgidra@google.com, surenb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+b446dbe27035ef6bd6c2@syzkaller.appspotmail.com, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: pa4a89io19kehdw3tdkwwomun9884yqg X-Rspamd-Queue-Id: 15BEC20011 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1753895257-485891 X-HE-Meta: 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 fzOV3uVz 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When UFFDIO_MOVE is used with UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES and it encounters a non-present THP, it fails to properly recognize an unmapped hole and tries to access a non-existent folio, resulting in a crash. Add a check to skip non-present THPs. Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Reported-by: syzbot+b446dbe27035ef6bd6c2@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68794b5c.a70a0220.693ce.0050.GAE@google.com/ Signed-off-by: Suren Baghdasaryan Cc: stable@vger.kernel.org --- mm/userfaultfd.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index cbed91b09640..60be8080ddd0 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1818,27 +1818,35 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start, ptl = pmd_trans_huge_lock(src_pmd, src_vma); if (ptl) { - /* Check if we can move the pmd without splitting it. */ - if (move_splits_huge_pmd(dst_addr, src_addr, src_start + len) || - !pmd_none(dst_pmdval)) { - struct folio *folio = pmd_folio(*src_pmd); + if (pmd_present(*src_pmd) || is_pmd_migration_entry(*src_pmd)) { + /* Check if we can move the pmd without splitting it. */ + if (move_splits_huge_pmd(dst_addr, src_addr, src_start + len) || + !pmd_none(dst_pmdval)) { + if (pmd_present(*src_pmd)) { + struct folio *folio = pmd_folio(*src_pmd); + + if (!folio || (!is_huge_zero_folio(folio) && + !PageAnonExclusive(&folio->page))) { + spin_unlock(ptl); + err = -EBUSY; + break; + } + } - if (!folio || (!is_huge_zero_folio(folio) && - !PageAnonExclusive(&folio->page))) { spin_unlock(ptl); - err = -EBUSY; - break; + split_huge_pmd(src_vma, src_pmd, src_addr); + /* The folio will be split by move_pages_pte() */ + continue; } + err = move_pages_huge_pmd(mm, dst_pmd, src_pmd, + dst_pmdval, dst_vma, src_vma, + dst_addr, src_addr); + } else { + /* nothing to do to move a hole */ spin_unlock(ptl); - split_huge_pmd(src_vma, src_pmd, src_addr); - /* The folio will be split by move_pages_pte() */ - continue; + err = 0; } - - err = move_pages_huge_pmd(mm, dst_pmd, src_pmd, - dst_pmdval, dst_vma, src_vma, - dst_addr, src_addr); step_size = HPAGE_PMD_SIZE; } else { if (pmd_none(*src_pmd)) { base-commit: 01da54f10fddf3b01c5a3b80f6b16bbad390c302 -- 2.50.1.552.g942d659e1b-goog