From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) (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 6EA522D9EF4 for ; Thu, 11 Dec 2025 11:19:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765451993; cv=none; b=Esg4ndmUYFAGGYEhLR+hScCnrSwmQVxte7tAwG67OPgE+skfXosJLggi0LCveU3O0GepK6TP+tTQLUp1v+qOmOlH5reiU0XLnB9ieJ9u1lhx16iMM3Mr+s3HgZeGQcX0TNMJpejaFTv8xGB0AbDl232kvsP5GY0yyF6RdHO4hak= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765451993; c=relaxed/simple; bh=JISBvzDqOGJstjAL+cgAOezJ+8sLO8V05l49b0sJ678=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=W24kLX0X4FPBRiO+Dw5O5B5qHN4qW+L1oy6JkecpGk60HogyP20tEUbc7Qs5qdPYpLwTZfbJZsJIEgOLIKzqOFiquX4Xuu8um4q88ney6xgUCGeZrYJWc2L1eKH9VayhGy0uOxJv7UNgrI4lJWFFhRNxSryoXf6PIG9jdh2n5lI= 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=L3ESy5vJ; arc=none smtp.client-ip=115.124.30.124 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="L3ESy5vJ" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1765451988; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=ecAkVjuCe9bGX9techowzEAb8Xjvjj2U4mfzWIwX6/A=; b=L3ESy5vJGxSLUGNF5lt7rRcU+QlA5MRITyNEZ4xqgHfvr+lRGUnXOX3GYivcj7Pc+shzTUXbv/CFqncWtxPeIJZsVyGe2wncMGgK0IHrbhka+AqMCRcY6r56mARvrny1epZAkeQtL5WjcZeIhCjwBzC8AtzF/vyDZOL+d/gF1Fc= Received: from 30.178.203.102(mailfrom:kanie@linux.alibaba.com fp:SMTPD_---0WuaG4L1_1765451986 cluster:ay36) by smtp.aliyun-inc.com; Thu, 11 Dec 2025 19:19:47 +0800 Message-ID: Date: Thu, 11 Dec 2025 19:19:46 +0800 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH v7 2/2] PCI: Check rom header and data structure addr before accessing To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= Cc: Bjorn Helgaas , Andy Shevchenko , linux-pci@vger.kernel.org References: <20251211033741.53072-1-kanie@linux.alibaba.com> <20251211033741.53072-3-kanie@linux.alibaba.com> From: Guixin Liu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/12/11 17:59, Ilpo Järvinen 写道: > On Thu, 11 Dec 2025, 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. >> >> Fixes: 47b975d234ea ("PCI: Avoid iterating through memory outside the resource window") >> Suggested-by: Guanghui Feng >> Signed-off-by: Guixin Liu >> Reviewed-by: Andy Shevchenko >> --- >> drivers/pci/rom.c | 119 +++++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 97 insertions(+), 22 deletions(-) >> >> diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c >> index 3e00611fa76b..8cbcc55946a4 100644 >> --- a/drivers/pci/rom.c >> +++ b/drivers/pci/rom.c >> @@ -10,6 +10,9 @@ >> #include >> #include >> #include >> +#include >> +#include >> +#include > Order. Sure. >> #include "pci.h" >> >> @@ -80,6 +83,87 @@ void pci_disable_rom(struct pci_dev *pdev) >> } >> EXPORT_SYMBOL_GPL(pci_disable_rom); >> >> +static bool pci_rom_is_header_valid(struct pci_dev *pdev, >> + void __iomem *image, >> + void __iomem *rom, >> + size_t size, >> + bool last_image) >> +{ >> + unsigned long rom_end = (unsigned long)rom + size - 1; >> + unsigned long header_end; >> + >> + /* >> + * Some CPU architectures require IOMEM access addresses to >> + * be aligned, for example arm64, so since we're about to >> + * call readw(), we check here for 2-byte alignment. >> + */ >> + if (!IS_ALIGNED((unsigned long)image, 2)) >> + return false; >> + >> + if (check_add_overflow((unsigned long)image, PCI_ROM_HEADER_SIZE, >> + &header_end)) >> + return false; >> + >> + if (image < rom || header_end > rom_end) >> + return false; >> + >> + /* Standard PCI ROMs start out with these bytes 55 AA */ >> + if (readw(image) == PCI_ROM_IMAGE_SIGNATURE) >> + return true; >> + >> + if (last_image) { >> + pci_info(pdev, "Invalid PCI ROM header signature: expecting %#06x, got %#06x\n", >> + PCI_ROM_IMAGE_SIGNATURE, readw(image)); > You should store the readw() value above as you use it here too so you > don't need to read it again. Sure. >> + } else { >> + pci_info(pdev, "No more image in the PCI ROM\n"); >> + } >> + >> + return false; >> +} >> + >> +static bool pci_rom_is_data_struct_valid(struct pci_dev *pdev, >> + void __iomem *pds, >> + void __iomem *rom, >> + size_t size) >> +{ >> + unsigned long rom_end = (unsigned long)rom + size - 1; >> + unsigned long end; >> + u16 data_len; >> + >> + /* >> + * Some CPU architectures require IOMEM access addresses to >> + * be aligned, for example arm64, so since we're about to >> + * call readl(), we check here for 4-byte alignment. >> + */ >> + if (!IS_ALIGNED((unsigned long)pds, 4)) >> + return false; >> + >> + /* Before reading length, check addr range. */ >> + if (check_add_overflow((unsigned long)pds, PCI_ROM_DATA_STRUCT_LEN + 1, >> + &end)) >> + return false; >> + >> + if (pds < rom || end > rom_end) >> + return false; >> + >> + data_len = readw(pds + PCI_ROM_DATA_STRUCT_LEN); >> + if (!data_len || data_len == U16_MAX) >> + return false; >> + >> + if (check_add_overflow((unsigned long)pds, data_len, &end)) >> + return false; >> + >> + if (end > rom_end) >> + return false; >> + >> + if (readl(pds) == PCI_ROM_DATA_STRUCT_SIGNATURE) >> + return true; >> + >> + pci_info(pdev, "Invalid PCI ROM data signature: expecting %#010x, got %#010x\n", >> + PCI_ROM_DATA_STRUCT_SIGNATURE, readl(pds)); > Ditto. > Sure. I will  change all in next version, thanks. Best Regards, Guixin Liu >> + return false; >> +} >> + >> /** >> * pci_get_rom_size - obtain the actual size of the ROM image >> * @pdev: target PCI device >> @@ -95,37 +179,28 @@ static size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, >> size_t size) >> { >> void __iomem *image; >> - int last_image; >> + bool last_image; >> unsigned int length; >> >> image = rom; >> do { >> void __iomem *pds; >> - /* Standard PCI ROMs start out with these bytes 55 AA */ >> - if (readw(image) != 0xAA55) { >> - pci_info(pdev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n", >> - readw(image)); >> + >> + if (!pci_rom_is_header_valid(pdev, image, rom, size, true)) >> break; >> - } >> + >> /* get the PCI data structure and check its "PCIR" signature */ >> - pds = image + readw(image + 24); >> - if (readl(pds) != 0x52494350) { >> - pci_info(pdev, "Invalid PCI ROM data signature: expecting 0x52494350, got %#010x\n", >> - readl(pds)); >> + pds = image + readw(image + PCI_ROM_POINTER_TO_DATA_STRUCT); >> + if (!pci_rom_is_data_struct_valid(pdev, pds, rom, size)) >> break; >> - } >> - last_image = readb(pds + 21) & 0x80; >> - length = readw(pds + 16); >> - image += length * 512; >> - /* Avoid iterating through memory outside the resource window */ >> - if (image >= rom + size) >> + >> + last_image = readb(pds + PCI_ROM_LAST_IMAGE_INDICATOR) & >> + PCI_ROM_LAST_IMAGE_INDICATOR_BIT; >> + length = readw(pds + PCI_ROM_IMAGE_LEN); >> + image += length * PCI_ROM_IMAGE_LEN_UNIT_SZ_512; >> + >> + if (!pci_rom_is_header_valid(pdev, image, rom, size, last_image)) >> break; >> - if (!last_image) { >> - if (readw(image) != 0xAA55) { >> - pci_info(pdev, "No more image in the PCI ROM\n"); >> - break; >> - } >> - } >> } while (length && !last_image); >> >> /* never return a size larger than the PCI resource window */ >>