From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) (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 62F3A1E570D for ; Wed, 26 Nov 2025 12:12:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.111 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764159159; cv=none; b=IoK0keRe6a3lb2EXzik+JIrr32Om9f3RlVcR/4XCmTQbEbDPsKFBJUvWfe//1H/qEuoYUw4fPIkOPin5+lOLHwQrzXrmhhcYcSVGJf2xCrV9oRaOJ1iiNWCAJbPhkL8n86xKMV715SuRs7r8pgATrnAKoq1thvunr5lCIIDxj0U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764159159; c=relaxed/simple; bh=usz/U/l0N+nytGhZ7cQNe0zBMm9SfDtdtArXdbnxjhU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GrW9Bwwloi2tiEcuUoXFdyjAKgryKqHm2GiyBi4VenhDEnTuzMBceYPTRpCBciU80taThQYaW4RkznkprDZZ54IwP9XUbDvWn699bSk1IFyyz9myZMGPRFJxswWFWYWiKTVxN6v7+AwR+Sw/2ytNxkDaWx6MUUgVaL95civ6zDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=alJ6xQj9; arc=none smtp.client-ip=115.124.30.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="alJ6xQj9" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1764159148; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=VVR1HD7IdKwqBQISA9xaA4jT30iUBaf+QNH/achBRs8=; b=alJ6xQj9HbneetRCRbwMHAMEYPp9f6SkY3mWrZ77hDxhdlrAV3RNQ8tZ+FvggSd/f3ukWNzkgzkIkuO2kY8e146XgkBWzh/F8pkKYS+dklkPCG0QmW0o9nrgGaTAVPwsrn1ScJKrzleWxUKeAutkhLPovUGnxjsEjFbbM/9ri7k= Received: from 30.178.240.57(mailfrom:kanie@linux.alibaba.com fp:SMTPD_---0WtSTZZw_1764159147 cluster:ay36) by smtp.aliyun-inc.com; Wed, 26 Nov 2025 20:12:27 +0800 Message-ID: Date: Wed, 26 Nov 2025 20:12:26 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH v3] PCI: Check rom header and data structure addr before accessing To: Andy Shevchenko Cc: Bjorn Helgaas , linux-kernel@vger.kernel.org References: <20251126072623.62579-1-kanie@linux.alibaba.com> From: Guixin Liu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/11/26 15:49, Andy Shevchenko 写道: > On Wed, Nov 26, 2025 at 03:26:23PM +0800, Guixin Liu wrote: >> We meet a crash when running stress-ng on x86_64 machine: >> >> BUG: unable to handle page fault for address: ffa0000007f40000 >> RIP: 0010:pci_get_rom_size+0x52/0x220 >> Call Trace: >> >> pci_map_rom+0x80/0x130 >> pci_read_rom+0x4b/0xe0 >> kernfs_file_read_iter+0x96/0x180 >> vfs_read+0x1b1/0x300 >> >> Our analysis reveals that the rom space's start address is >> 0xffa0000007f30000, and size is 0x10000. Because of broken rom >> space, before calling readl(pds), the pds's value is >> 0xffa0000007f3ffff, which is already pointed to the rom space >> end, invoking readl() would read 4 bytes therefore cause an >> out-of-bounds access and trigger a crash. >> Fix this by adding image header and data structure checking. >> >> We also found another crash on arm64 machine: >> >> Unable to handle kernel paging request at virtual address >> ffff8000dd1393ff >> Mem abort info: >> ESR = 0x0000000096000021 >> EC = 0x25: DABT (current EL), IL = 32 bits >> SET = 0, FnV = 0 >> EA = 0, S1PTW = 0 >> FSC = 0x21: alignment fault >> >> The call trace is the same with x86_64, but the crash reason is >> that the data structure addr is not aligned with 4, and arm64 >> machine report "alignment fault". Fix this by adding alignment >> checking. > Thanks for the update, looks much better now! > My comments below. > > ... > >> +static inline bool pci_rom_header_valid(struct pci_dev *pdev, >> + void __iomem *image, >> + void __iomem *rom, >> + size_t size, >> + bool last_image) >> +{ >> + uintptr_t rom_end = (uintptr_t)rom + size; >> + uintptr_t header_end; > Note: Linus told that kernel should not use uintptr_t. > > s/uintptr_t/unsigned long/g > > and here in some cases we even don't need that type at all. OK, changed in v4. >> + if (check_add_overflow((uintptr_t)image, PCI_ROM_HEADER_SIZE, >> + &header_end)) >> + return false; >> + if (image >= rom && header_end < rom_end && >> + IS_ALIGNED((uintptr_t)image, 2)) { > So, why not > > /* Check if we have enough space in ROM */ > if (image < rom || header_end > rom_end) > return false; OK, will be changed in v4. > /* ARM requires proper alignment */ > /// Find a better comment text for above. > if (!IS_ALIGNED((unsigned long)image, 2UL)) > return false; Sure. >> + /* Standard PCI ROMs start out with these bytes 55 AA */ >> + if (readw(image) == 0xAA55) >> + return true; >> + >> + if (!last_image) >> + pci_info(pdev, "No more image in the PCI ROM\n"); >> + else >> + pci_info(pdev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n", >> + readw(image)); >> + } >> + return false; >> +} > ... > >> +static inline bool pci_rom_data_struct_valid(struct pci_dev *pdev, >> + void __iomem *pds, >> + void __iomem *rom, >> + size_t size) > Similar comments as per above. > > ... > >> image = rom; >> do { >> void __iomem *pds; >> + >> + if (!pci_rom_header_valid(pdev, image, rom, size, true)) >> break; >> + >> /* get the PCI data structure and check its "PCIR" signature */ >> pds = image + readw(image + 24); >> + if (!pci_rom_data_struct_valid(pdev, pds, rom, size)) >> break; >> + >> last_image = readb(pds + 21) & 0x80; >> length = readw(pds + 16); >> image += length * 512; >> + if (!pci_rom_header_valid(pdev, image, rom, size, (bool)last_image)) > This casting is a bit odd. Can we avoid doing like this? Emm, not think too much, I will change last_iamge to bool in v4. Best Regards, Guixin Liu >> } while (length && !last_image);