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firmware: google: Add bounds checks in coreboot_table_populate()

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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>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Link: https://lore.kernel.org/r/20260426214739.117131-1-titouan.ameline@gmail.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
This commit is contained in:
Titouan Ameline de Cadeville 2026-04-26 23:47:39 +02:00 committed by Tzung-Bi Shih
parent 254f49634e
commit 7b1a1af455
1 changed files with 9 additions and 2 deletions
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11
drivers/firmware/google/coreboot_table.c
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@ -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);