From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 97A2014B075; Wed, 5 Mar 2025 18:00:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741197650; cv=none; b=SwLFlqqHZATqng5bLygpggX4KI+diAAa2s4PUmogD2KQbhC9FOgKQGPx2GcrVMxbcb0mX4sKnVacdWg2TRxWP39ZXMsNhWsr/uBvu6emZHLiUOfBJaIllexc302RtyHDrJ0CYTAZUwBeEDPj9+zradWGzHrbxqfkhRCoSBZfPhg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741197650; c=relaxed/simple; bh=13DtybAkjUmKqDEBq8Q7l/B3on1ZTxlmL/dDJeV4ogE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MuDvUEKNa2LSgzJPRNqrS1KsZUOk2hZbYdNswN1c0MDeN7XKwt97vDN/uQtg5XEQTraAD9961TQSIv2up+hmY0B4uRFDUjP+xC3MUlUTFiTtzaWfUSE/JaBIO3R460iPyZHf8GtuN2goV0aJwioOax6WlbuTWvWqcprMVYy7xNw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JhZcVrEK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="JhZcVrEK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EB11C4CED1; Wed, 5 Mar 2025 18:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741197650; bh=13DtybAkjUmKqDEBq8Q7l/B3on1ZTxlmL/dDJeV4ogE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JhZcVrEKCbtahQ/0PyFmZPhlYVN52FvS62SJlDFatiqoO0ZHixqNUcc4NNec08cxM 87izibhGxwbgLVluvCyQvbjw3+fCNfBdqyr4uaF37v1lhOJmfCQdrxkFon51sIHL0N lX/t3c8c3RmX09fSFR1eIPCkwglQo8X8JHaPALGU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tong Tiangen , Ingo Molnar , David Hildenbrand , Oleg Nesterov , Peter Zijlstra , Masami Hiramatsu , Sasha Levin Subject: [PATCH 6.6 053/142] uprobes: Reject the shared zeropage in uprobe_write_opcode() Date: Wed, 5 Mar 2025 18:47:52 +0100 Message-ID: <20250305174502.468970216@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250305174500.327985489@linuxfoundation.org> References: <20250305174500.327985489@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tong Tiangen [ Upstream commit bddf10d26e6e5114e7415a0e442ec6f51a559468 ] We triggered the following crash in syzkaller tests: BUG: Bad page state in process syz.7.38 pfn:1eff3 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3 flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff) raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000 raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x32/0x50 bad_page+0x69/0xf0 free_unref_page_prepare+0x401/0x500 free_unref_page+0x6d/0x1b0 uprobe_write_opcode+0x460/0x8e0 install_breakpoint.part.0+0x51/0x80 register_for_each_vma+0x1d9/0x2b0 __uprobe_register+0x245/0x300 bpf_uprobe_multi_link_attach+0x29b/0x4f0 link_create+0x1e2/0x280 __sys_bpf+0x75f/0xac0 __x64_sys_bpf+0x1a/0x30 do_syscall_64+0x56/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1 The following syzkaller test case can be used to reproduce: r2 = creat(&(0x7f0000000000)='./file0\x00', 0x8) write$nbd(r2, &(0x7f0000000580)=ANY=[], 0x10) r4 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x42, 0x0) mmap$IORING_OFF_SQ_RING(&(0x7f0000ffd000/0x3000)=nil, 0x3000, 0x0, 0x12, r4, 0x0) r5 = userfaultfd(0x80801) ioctl$UFFDIO_API(r5, 0xc018aa3f, &(0x7f0000000040)={0xaa, 0x20}) r6 = userfaultfd(0x80801) ioctl$UFFDIO_API(r6, 0xc018aa3f, &(0x7f0000000140)) ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, &(0x7f0000000100)={{&(0x7f0000ffc000/0x4000)=nil, 0x4000}, 0x2}) ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, &(0x7f0000000000)={{&(0x7f0000ffd000/0x1000)=nil, 0x1000}}) r7 = bpf$PROG_LOAD(0x5, &(0x7f0000000140)={0x2, 0x3, &(0x7f0000000200)=ANY=[@ANYBLOB="1800000000120000000000000000000095"], &(0x7f0000000000)='GPL\x00', 0x7, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @fallback=0x30, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_LINK_CREATE_XDP(0x1c, &(0x7f0000000040)={r7, 0x0, 0x30, 0x1e, @val=@uprobe_multi={&(0x7f0000000080)='./file0\x00', &(0x7f0000000100)=[0x2], 0x0, 0x0, 0x1}}, 0x40) The cause is that zero pfn is set to the PTE without increasing the RSS count in mfill_atomic_pte_zeropage() and the refcount of zero folio does not increase accordingly. Then, the operation on the same pfn is performed in uprobe_write_opcode()->__replace_page() to unconditional decrease the RSS count and old_folio's refcount. Therefore, two bugs are introduced: 1. The RSS count is incorrect, when process exit, the check_mm() report error "Bad rss-count". 2. The reserved folio (zero folio) is freed when folio->refcount is zero, then free_pages_prepare->free_page_is_bad() report error "Bad page state". There is more, the following warning could also theoretically be triggered: __replace_page() -> ... -> folio_remove_rmap_pte() -> VM_WARN_ON_FOLIO(is_zero_folio(folio), folio) Considering that uprobe hit on the zero folio is a very rare case, just reject zero old folio immediately after get_user_page_vma_remote(). [ mingo: Cleaned up the changelog ] Fixes: 7396fa818d62 ("uprobes/core: Make background page replacement logic account for rss_stat counters") Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Signed-off-by: Tong Tiangen Signed-off-by: Ingo Molnar Reviewed-by: David Hildenbrand Reviewed-by: Oleg Nesterov Cc: Peter Zijlstra Cc: Masami Hiramatsu Link: https://lore.kernel.org/r/20250224031149.1598949-1-tongtiangen@huawei.com Signed-off-by: Sasha Levin --- kernel/events/uprobes.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 6dac0b5798213..7e2edd1b06939 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -481,6 +481,11 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, if (ret <= 0) goto put_old; + if (is_zero_page(old_page)) { + ret = -EINVAL; + goto put_old; + } + if (WARN(!is_register && PageCompound(old_page), "uprobe unregister should never work on compound page\n")) { ret = -EINVAL; -- 2.39.5