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Mon, 26 Oct 2026 06:09:29 +0000 X-Mizu-Trace-ID: f1f0116670f74061 X-Migadu-Flow: FLOW_OUT From: Ye Liu Subject: [PATCH 0/2] mm/vmalloc: harden remap_vmalloc_range_partial against NULL pages Date: Mon, 26 Oct 2026 14:09:22 +0800 Message-Id: <20261026-vmalloc_remap-v1-0-b7a907814e90@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAJLu3moC/yXMywqAIBCF4VeJWSeoREivEhE2TTXRDS0JonfPa nEW3+L8F3hyTB6K5AJHgT2vS4RKE8DBLj0JbqNBS52rOBFmO00r1o5muwmpNHaZMqitgfjZHHV 8fr2y+u2PZiTc3wjc9wPSLN5scQAAAA== X-Change-ID: 20261026-vmalloc_remap-012cf418c2a8 To: Andrew Morton , Uladzislau Rezki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ye Liu X-Mailer: b4 0.17-dev-39d60 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: EF84F140002 X-Stat-Signature: j7mw3ap9zztheuu8zjxqtcfrbdq9iehm X-Spam-Status: No, score=-23.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_PASS,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1792994970-366724 X-HE-Meta: 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 MX6o4qMI I7hJi+YyodffSBGEmXDwf77CruLYGXXE3Z0UZuaA6kSfgowLl/LgyMmdZhF/QHNCsz+BO6RwaB/vThU2WGG+LayOIMh1btT/cVWVm29KAm21OEE3ewLDnQGPhztqC8sX2NL56H5fbDqymfdfDIUo7mpQUyHD46ovmNEuoQd0C36z4bLFGaK1hhxz5SOZ4b4XZJBR15vBgky7QVwHG7ycRH9WVtnaxte+i6X1WVLw6utJ4U+cJQ+mKuvE49atUS5gvYpjo/6gt5OFIaSkJ/zL62BpRqOwLF9uZZFBkq5ZcoroxWtP4Pjaa9wDUUw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 remap_vmalloc_range_partial() passes vmalloc_to_page()'s result to vm_insert_page() unchecked, oopsing via page_folio() if the page is NULL. The NULL case never happens today because VM_USERMAP areas keep every page mapped, but that assumption is nowhere checked. Patch 1 drops VM_DMA_COHERENT from the allow-list -- a dead entry (no caller maps a DMA-coherent area through this path) whose presence also opens a NULL-deref path, since VM_DMA_COHERENT is not in vrealloc's shrink skip-list. Patch 2 adds a WARN_ON(!page) to flag any future break at the vmalloc_to_page() call site before the oops. Patch 1 is a behavior change (no in-tree caller affected); Patch 2 is dead code. The two are independent. Signed-off-by: Ye Liu --- Ye Liu (2): mm/vmalloc: drop VM_DMA_COHERENT from remap_vmalloc_range_partial mm/vmalloc: warn on NULL page in remap_vmalloc_range_partial mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- base-commit: 2efb7a11f1aa4d2dc285fe2680cca22cb9f72f64 base-tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master change-id: 20261026-vmalloc_remap-012cf418c2a8 Best regards, -- Ye Liu