[PATCH] firmware: google: add bounds checks in coreboot_table_populate()

Titouan Ameline de Cadeville
2026-04-26T21:47:56Z

coreboot_table_populate() iterates over firmware-provided table entries
with no validation that the entries stay within the mapped memory region.
A corrupt table with a large entry->size advances ptr_entry past the
mapped region, causing an out-of-bounds read on the next iteration.

Add a check before dereferencing ptr_entry to ensure the entry header
is readable, and a second check after reading entry->size to ensure the
full entry stays within the mapped region.

Pass len from coreboot_table_probe() into coreboot_table_populate() to
make the mapped region size available for validation.

Signed-off-by: Titouan Ameline de Cadeville <titouan.ameline@gmail.com>
---
drivers/firmware/google/coreboot_table.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c
index c769631ea15d..233939e548b4 100644
--- a/drivers/firmware/google/coreboot_table.c
+++ b/drivers/firmware/google/coreboot_table.c
@@ -112,16 +112,20 @@ void coreboot_driver_unregister(struct coreboot_driver *driver)
}
EXPORT_SYMBOL(coreboot_driver_unregister);

-static int coreboot_table_populate(struct device *dev, void *ptr)
+static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_t len)
{
int i, ret;
void *ptr_entry;
struct coreboot_device *device;
struct coreboot_table_entry *entry;
struct coreboot_table_header *header = ptr;
+ void *ptr_end;

+ ptr_end = ptr + len;
ptr_entry = ptr + header->header_bytes;
for (i = 0; i < header->table_entries; i++) {
+ if (ptr_entry + sizeof(*entry) > ptr_end)
+ return -EINVAL;
entry = ptr_entry;

if (entry->size < sizeof(*entry)) {
@@ -129,6 +133,9 @@ static int coreboot_table_populate(struct device *dev, void *ptr)
return -EINVAL;
}

+ if (ptr_entry + entry->size > ptr_end)
+ return -EINVAL;
+
device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
if (!device)
return -ENOMEM;
@@ -194,7 +201,7 @@ static int coreboot_table_probe(struct platform_device *pdev)
if (!ptr)
return -ENOMEM;

- ret = coreboot_table_populate(dev, ptr);
+ ret = coreboot_table_populate(dev, ptr, len);

memunmap(ptr);

--
2.44.2