From nobody Sat Feb 7 17:20:51 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7E46C001DE for ; Fri, 28 Jul 2023 10:55:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236058AbjG1Kz2 (ORCPT ); Fri, 28 Jul 2023 06:55:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232465AbjG1Kz1 (ORCPT ); Fri, 28 Jul 2023 06:55:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 306D71BC6 for ; Fri, 28 Jul 2023 03:55:26 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B26B3620CE for ; Fri, 28 Jul 2023 10:55:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34CC4C433C7; Fri, 28 Jul 2023 10:55:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690541725; bh=KiJekQvrYKFV+Wo4fuymS0vHZbJ6vimMcoU3XpuBEPc=; h=From:To:Cc:Subject:Date:From; b=iGq+jEykNKtWVUol0RQTBkbIWYLn8/FBSfap1epA8o9SY3qb/5N3iGUDWf825Abav JEkTq72fJEq04tlkQxBvomBVqIdYCNkS6tAZ4La1fO0OejVen4VwVXIWs/14R8qsAc Lptjb5BYmOUtn4nb1WfBgvCvs8Cadv7bs7g7jZs18LOwt3TyJdEZijYh6cLvhdd/TW fPKuwexfJuc15t4AFHSfr5Nx71yz4sWiY12i6TkU26F7ea3lZShUf/S9apGqtK3iPP +SDL0W7L1lbDg7aLxZ2jDjyji3aOdbNFdU8jB54uvl5lNv52XgaEExmkzt8I/GDpdJ iqcP3WJIs85+A== From: Mike Rapoport To: Linus Torvalds Cc: Andrew Morton , Mike Rapoport , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel test robot Subject: [PATCH] Revert "mm,memblock: reset memblock.reserved to system init state to prevent UAF" Date: Fri, 28 Jul 2023 13:55:12 +0300 Message-Id: <20230728105512.2258393-1-rppt@kernel.org> X-Mailer: git-send-email 2.39.2 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" From: "Mike Rapoport (IBM)" This reverts commit 9e46e4dcd9d6cd88342b028dbfa5f4fb7483d39c. kbuild reports a warning in memblock_remove_region() because of a false positive caused by partial reset of the memblock state. Doing the full reset will remove the false positives, but will allow late use of memblock_free() to go unnoticed, so it is better to revert the offending commit. WARNING: CPU: 0 PID: 1 at mm/memblock.c:352 memblock_remove_region (kbuild= /src/x86_64/mm/memblock.c:352 (discriminator 1)) Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc3-00001-g9e46e4dcd9d6 #2 RIP: 0010:memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (dis= criminator 1)) Code: 00 00 48 8b 43 18 48 c7 40 08 00 00 00 00 48 8b 43 18 c7 40 10 00 00= 00 00 48 8b 43 18 c7 40 14 00 04 00 00 5b c3 cc cc cc cc <0f> 0b eb c2 66 = 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 RSP: 0000:ffa0000000077e78 EFLAGS: 00010206 RAX: ffffffff82f4bc40 RBX: ffffffff82f4bc18 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff82f4bc58 RDI: ffffffff82f4bc40 RBP: 0000000000000000 R08: ff1100207ffd4d00 R09: 0000000000000002 R10: ffd4000081ff9d00 R11: ff1100207ffd4000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ff1100103f200000(0000) knlGS:00000000000000= 00 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ff1100207fc00000 CR3: 000000207ea18001 CR4: 0000000000771ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminat= or 1)) ? __warn (kbuild/src/x86_64/kernel/panic.c:673) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminat= or 1)) ? report_bug (kbuild/src/x86_64/lib/bug.c:180 kbuild/src/x86_64/lib/bug.c:= 219) ? handle_bug (kbuild/src/x86_64/arch/x86/kernel/traps.c:324) ? exc_invalid_op (kbuild/src/x86_64/arch/x86/kernel/traps.c:345 (discrimin= ator 1)) ? asm_exc_invalid_op (kbuild/src/x86_64/arch/x86/include/asm/idtentry.h:56= 8) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminat= or 1)) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:348) memblock_discard (kbuild/src/x86_64/mm/memblock.c:383) page_alloc_init_late (kbuild/src/x86_64/include/linux/find.h:208 kbuild/sr= c/x86_64/include/linux/nodemask.h:266 kbuild/src/x86_64/mm/mm_init.c:2405) kernel_init_freeable (kbuild/src/x86_64/init/main.c:1325 kbuild/src/x86_64= /init/main.c:1546) ? __pfx_kernel_init (kbuild/src/x86_64/init/main.c:1429) kernel_init (kbuild/src/x86_64/init/main.c:1439) ret_from_fork (kbuild/src/x86_64/arch/x86/kernel/process.c:145) ? __pfx_kernel_init (kbuild/src/x86_64/init/main.c:1429) ret_from_fork_asm (kbuild/src/x86_64/arch/x86/entry/entry_64.S:298) RIP: 0000:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0000:0000000000000000 EFLAGS: 00000000 ORIG_RAX: 0000000000000000 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202307271656.447aa17e-oliver.sang@in= tel.com Signed-off-by: Mike Rapoport (IBM) --- Hi, Looks like I didn't wait enough for kbuild :( Linus, do you prefer a pull request or to pick it right away? mm/memblock.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index c39b36378f5d..f9e61e565a53 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -374,10 +374,6 @@ void __init memblock_discard(void) kfree(memblock.reserved.regions); else memblock_free_late(addr, size); - /* Reset to prevent UAF from stray frees. */ - memblock.reserved.regions =3D memblock_reserved_init_regions; - memblock.reserved.cnt =3D 1; - memblock_remove_region(&memblock.reserved, 0); } =20 if (memblock.memory.regions !=3D memblock_memory_init_regions) { --=20 2.39.2