From: Kees Cook keescook@chromium.org
[ Upstream commit 3b293487b8752cc42c1cbf8a0447bc6076c075fa ]
The memcpy() of the data following a coreboot_table_entry couldn't be evaluated by the compiler under CONFIG_FORTIFY_SOURCE. To make it easier to reason about, add an explicit flexible array member to struct coreboot_device so the entire entry can be copied at once. Additionally, validate the sizes before copying. Avoids this run-time false positive warning:
memcpy: detected field-spanning write (size 168) of single field "&device->entry" at drivers/firmware/google/coreboot_table.c:103 (size 8)
Reported-by: Paul Menzel pmenzel@molgen.mpg.de Link: https://lore.kernel.org/all/03ae2704-8c30-f9f0-215b-7cdf4ad35a9a@molgen.mpg.... Cc: Jack Rosenthal jrosenth@chromium.org Cc: Guenter Roeck groeck@chromium.org Cc: Julius Werner jwerner@chromium.org Cc: Brian Norris briannorris@chromium.org Cc: Stephen Boyd swboyd@chromium.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Julius Werner jwerner@chromium.org Reviewed-by: Guenter Roeck groeck@chromium.org Link: https://lore.kernel.org/r/20230107031406.gonna.761-kees@kernel.org Reviewed-by: Stephen Boyd swboyd@chromium.org Reviewed-by: Jack Rosenthal jrosenth@chromium.org Link: https://lore.kernel.org/r/20230112230312.give.446-kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/google/coreboot_table.c | 9 +++++++-- drivers/firmware/google/coreboot_table.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c index 9ca21feb9d45..f3694d347801 100644 --- a/drivers/firmware/google/coreboot_table.c +++ b/drivers/firmware/google/coreboot_table.c @@ -93,7 +93,12 @@ static int coreboot_table_populate(struct device *dev, void *ptr) for (i = 0; i < header->table_entries; i++) { entry = ptr_entry;
- device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL); + if (entry->size < sizeof(*entry)) { + dev_warn(dev, "coreboot table entry too small!\n"); + return -EINVAL; + } + + device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL); if (!device) return -ENOMEM;
@@ -101,7 +106,7 @@ static int coreboot_table_populate(struct device *dev, void *ptr) device->dev.parent = dev; device->dev.bus = &coreboot_bus_type; device->dev.release = coreboot_device_release; - memcpy(&device->entry, ptr_entry, entry->size); + memcpy(device->raw, ptr_entry, entry->size);
ret = device_register(&device->dev); if (ret) { diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/google/coreboot_table.h index beb778674acd..4a89277b99a3 100644 --- a/drivers/firmware/google/coreboot_table.h +++ b/drivers/firmware/google/coreboot_table.h @@ -66,6 +66,7 @@ struct coreboot_device { struct coreboot_table_entry entry; struct lb_cbmem_ref cbmem_ref; struct lb_framebuffer framebuffer; + DECLARE_FLEX_ARRAY(u8, raw); }; };