From a58a57a1076f8c5dae0327e3710899478c3be901 Mon Sep 17 00:00:00 2001 From: Laxman Acharya Padhya Date: Sat, 1 Aug 2026 22:41:51 +0545 Subject: [PATCH] firmware: coreboot: Validate table bounds The existing coreboot_table_populate() bounds checks limit individual entries to the mapped length. However, coreboot_table_probe() replaces the platform resource length with header and table sizes supplied by firmware before mapping the full table. A malformed table can overflow the 32-bit size addition or advertise an extent beyond the resource, causing the driver to map and parse memory outside the resource. A resource shorter than the fixed header is also mapped as though it contained a complete header. Reject resources shorter than the fixed header. After validating the signature, require a complete header, calculate the advertised extent with overflow checking, and reject extents beyond the resource before remapping the table. Fixes: d384d6f43d1e ("firmware: google memconsole: Add coreboot support") Signed-off-by: Laxman Acharya Padhya Link: https://lore.kernel.org/r/20260801165651.42172-1-acharyalaxman8848@gmail.com Signed-off-by: Tzung-Bi Shih --- drivers/firmware/google/coreboot_table.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c index 993056a739ad..25ee8cf53429 100644 --- a/drivers/firmware/google/coreboot_table.c +++ b/drivers/firmware/google/coreboot_table.c @@ -190,6 +190,7 @@ static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_ static int coreboot_table_probe(struct platform_device *pdev) { resource_size_t len; + resource_size_t table_span; struct coreboot_table_header *header; struct resource *res; struct device *dev = &pdev->dev; @@ -201,7 +202,7 @@ static int coreboot_table_probe(struct platform_device *pdev) return -EINVAL; len = resource_size(res); - if (!res->start || !len) + if (!res->start || len < sizeof(*header)) return -EINVAL; /* Check just the header first to make sure things are sane */ @@ -209,19 +210,27 @@ static int coreboot_table_probe(struct platform_device *pdev) if (!header) return -ENOMEM; - len = header->header_bytes + header->table_bytes; ret = strncmp(header->signature, "LBIO", sizeof(header->signature)); + + if (!ret && + (header->header_bytes < sizeof(*header) || + check_add_overflow((resource_size_t)header->header_bytes, + (resource_size_t)header->table_bytes, + &table_span) || + table_span > len)) + ret = -EINVAL; + memunmap(header); if (ret) { dev_warn(dev, "coreboot table missing or corrupt!\n"); return -ENODEV; } - ptr = memremap(res->start, len, MEMREMAP_WB); + ptr = memremap(res->start, table_span, MEMREMAP_WB); if (!ptr) return -ENOMEM; - ret = coreboot_table_populate(dev, ptr, len); + ret = coreboot_table_populate(dev, ptr, table_span); memunmap(ptr);