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![Robert Richter](/assets/img/avatar_default.png)
There exist card implementations with a CDAT table using a fixed size buffer, but with entries filled in that do not fill the whole table length size. Then, the last entry in the CDAT table may not mark the end of the CDAT table buffer specified by the length field in the CDAT header. It can be shorter with trailing unused (zero'ed) data. The actual table length is determined while reading all CDAT entries of the table with DOE. If the table is greater than expected (containing zero'ed trailing data), the CDAT parser fails with: [ 48.691717] Malformed DSMAS table length: (24:0) [ 48.702084] [CDAT:0x00] Invalid zero length [ 48.711460] cxl_port endpoint1: Failed to parse CDAT: -22 In addition, a check of the table buffer length is missing to prevent an out-of-bound access then parsing the CDAT table. Hardening code against device returning borked table. Fix that by providing an optional buffer length argument to acpi_parse_entries_array() that can be used by cdat_table_parse() to propagate the buffer size down to its users to check the buffer length. This also prevents a possible out-of-bound access mentioned. Add a check to warn about a malformed CDAT table length. Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Len Brown <lenb@kernel.org> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Robert Richter <rrichter@amd.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/ZdEnopFO0Tl3t2O1@rric.localdomain Signed-off-by: Dan Williams <dan.j.williams@intel.com>
233 lines
6.1 KiB
C
233 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
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* platform or device firmware
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*
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* Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
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* Copyright (C) 2023 Intel Corp.
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*/
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#include <linux/errno.h>
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#include <linux/acpi.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/fw_table.h>
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enum acpi_subtable_type {
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ACPI_SUBTABLE_COMMON,
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ACPI_SUBTABLE_HMAT,
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ACPI_SUBTABLE_PRMT,
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ACPI_SUBTABLE_CEDT,
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CDAT_SUBTABLE,
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};
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struct acpi_subtable_entry {
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union acpi_subtable_headers *hdr;
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enum acpi_subtable_type type;
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};
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static unsigned long __init_or_fwtbl_lib
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acpi_get_entry_type(struct acpi_subtable_entry *entry)
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{
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switch (entry->type) {
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case ACPI_SUBTABLE_COMMON:
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return entry->hdr->common.type;
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case ACPI_SUBTABLE_HMAT:
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return entry->hdr->hmat.type;
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case ACPI_SUBTABLE_PRMT:
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return 0;
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case ACPI_SUBTABLE_CEDT:
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return entry->hdr->cedt.type;
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case CDAT_SUBTABLE:
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return entry->hdr->cdat.type;
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}
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return 0;
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}
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static unsigned long __init_or_fwtbl_lib
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acpi_get_entry_length(struct acpi_subtable_entry *entry)
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{
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switch (entry->type) {
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case ACPI_SUBTABLE_COMMON:
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return entry->hdr->common.length;
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case ACPI_SUBTABLE_HMAT:
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return entry->hdr->hmat.length;
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case ACPI_SUBTABLE_PRMT:
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return entry->hdr->prmt.length;
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case ACPI_SUBTABLE_CEDT:
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return entry->hdr->cedt.length;
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case CDAT_SUBTABLE: {
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__le16 length = (__force __le16)entry->hdr->cdat.length;
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return le16_to_cpu(length);
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}
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}
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return 0;
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}
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static unsigned long __init_or_fwtbl_lib
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acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
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{
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switch (entry->type) {
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case ACPI_SUBTABLE_COMMON:
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return sizeof(entry->hdr->common);
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case ACPI_SUBTABLE_HMAT:
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return sizeof(entry->hdr->hmat);
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case ACPI_SUBTABLE_PRMT:
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return sizeof(entry->hdr->prmt);
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case ACPI_SUBTABLE_CEDT:
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return sizeof(entry->hdr->cedt);
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case CDAT_SUBTABLE:
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return sizeof(entry->hdr->cdat);
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}
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return 0;
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}
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static enum acpi_subtable_type __init_or_fwtbl_lib
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acpi_get_subtable_type(char *id)
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{
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if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
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return ACPI_SUBTABLE_HMAT;
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if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
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return ACPI_SUBTABLE_PRMT;
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if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
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return ACPI_SUBTABLE_CEDT;
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if (strncmp(id, ACPI_SIG_CDAT, 4) == 0)
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return CDAT_SUBTABLE;
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return ACPI_SUBTABLE_COMMON;
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}
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static unsigned long __init_or_fwtbl_lib
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acpi_table_get_length(enum acpi_subtable_type type,
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union fw_table_header *header)
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{
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if (type == CDAT_SUBTABLE) {
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__le32 length = (__force __le32)header->cdat.length;
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return le32_to_cpu(length);
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}
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return header->acpi.length;
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}
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static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc,
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union acpi_subtable_headers *hdr,
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unsigned long end)
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{
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if (proc->handler)
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return proc->handler(hdr, end);
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if (proc->handler_arg)
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return proc->handler_arg(hdr, proc->arg, end);
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return -EINVAL;
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}
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/**
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* acpi_parse_entries_array - for each proc_num find a suitable subtable
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*
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* @id: table id (for debugging purposes)
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* @table_size: size of the root table
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* @max_length: maximum size of the table (ignore if 0)
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* @table_header: where does the table start?
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* @proc: array of acpi_subtable_proc struct containing entry id
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* and associated handler with it
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* @proc_num: how big proc is?
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* @max_entries: how many entries can we process?
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*
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* For each proc_num find a subtable with proc->id and run proc->handler
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* on it. Assumption is that there's only single handler for particular
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* entry id.
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*
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* The table_size is not the size of the complete ACPI table (the length
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* field in the header struct), but only the size of the root table; i.e.,
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* the offset from the very first byte of the complete ACPI table, to the
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* first byte of the very first subtable.
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*
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* On success returns sum of all matching entries for all proc handlers.
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* Otherwise, -ENODEV or -EINVAL is returned.
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*/
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int __init_or_fwtbl_lib
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acpi_parse_entries_array(char *id, unsigned long table_size,
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union fw_table_header *table_header,
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unsigned long max_length,
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struct acpi_subtable_proc *proc,
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int proc_num, unsigned int max_entries)
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{
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unsigned long table_len, table_end, subtable_len, entry_len;
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struct acpi_subtable_entry entry;
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enum acpi_subtable_type type;
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int count = 0;
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int i;
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type = acpi_get_subtable_type(id);
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table_len = acpi_table_get_length(type, table_header);
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if (max_length && max_length < table_len)
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table_len = max_length;
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table_end = (unsigned long)table_header + table_len;
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/* Parse all entries looking for a match. */
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entry.type = type;
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entry.hdr = (union acpi_subtable_headers *)
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((unsigned long)table_header + table_size);
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subtable_len = acpi_get_subtable_header_length(&entry);
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while (((unsigned long)entry.hdr) + subtable_len < table_end) {
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for (i = 0; i < proc_num; i++) {
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if (acpi_get_entry_type(&entry) != proc[i].id)
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continue;
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if (!max_entries || count < max_entries)
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if (call_handler(&proc[i], entry.hdr, table_end))
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return -EINVAL;
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proc[i].count++;
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count++;
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break;
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}
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/*
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* If entry->length is 0, break from this loop to avoid
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* infinite loop.
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*/
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entry_len = acpi_get_entry_length(&entry);
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if (entry_len == 0) {
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pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
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return -EINVAL;
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}
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entry.hdr = (union acpi_subtable_headers *)
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((unsigned long)entry.hdr + entry_len);
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}
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if (max_entries && count > max_entries) {
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pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
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id, proc->id, count - max_entries, count);
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}
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return count;
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}
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int __init_or_fwtbl_lib
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cdat_table_parse(enum acpi_cdat_type type,
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acpi_tbl_entry_handler_arg handler_arg,
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void *arg,
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struct acpi_table_cdat *table_header,
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unsigned long length)
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{
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struct acpi_subtable_proc proc = {
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.id = type,
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.handler_arg = handler_arg,
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.arg = arg,
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};
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if (!table_header)
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return -EINVAL;
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return acpi_parse_entries_array(ACPI_SIG_CDAT,
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sizeof(struct acpi_table_cdat),
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(union fw_table_header *)table_header,
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length, &proc, 1, 0);
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}
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EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);
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