6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Laxman Acharya Padhya <redacted>
[ Upstream commit a58a57a1076f8c5dae0327e3710899478c3be901 ]
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 <redacted>
Link: https://lore.kernel.org/r/20260801165651.42172-1-acharyalaxman8848@gmail.com (local)
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 95fc2e4d0cccf..7d7a6a1a2ac07 100644
--- a/drivers/firmware/google/coreboot_table.c
+++ b/drivers/firmware/google/coreboot_table.c
@@ -130,6 +130,7 @@ 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;@@ -141,7 +142,7 @@ 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 */
@@ -149,19 +150,27 @@ 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);
--
2.53.0