Hi Nathan,
On Mon, Aug 19, 2024 at 12:09 PM Nathan Chancellor nathan@kernel.org wrote:
When an attribute group is created with sysfs_create_group(), the ->sysfs_ops() callback is set to kobj_sysfs_ops, which sets the ->show() and ->store() callbacks to kobj_attr_show() and kobj_attr_store() respectively. These functions use container_of() to get the respective callback from the passed attribute, meaning that these callbacks need to be the same type as the callbacks in 'struct kobj_attribute'.
However, the platform_profile sysfs functions have the type of the ->show() and ->store() callbacks in 'struct device_attribute', which results a CFI violation when accessing platform_profile or platform_profile_choices under /sys/firmware/acpi because the types do not match:
CFI failure at kobj_attr_show+0x19/0x30 (target: platform_profile_choices_show+0x0/0x140; expected type: 0x7a69590c)
This happens to work because the layout of 'struct kobj_attribute' and 'struct device_attribute' are the same, so the container_of() cast happens to allow the callbacks to still work.
Change the type of platform_profile_choices_show() and platform_profile_{show,store}() to match the callbacks in 'struct kobj_attribute' and update the attribute variables to match, which resolves the CFI violation.
Cc: stable@vger.kernel.org Fixes: a2ff95e018f1 ("ACPI: platform: Add platform profile support") Reported-by: John Rowley lkml@johnrowley.me Closes: https://github.com/ClangBuiltLinux/linux/issues/2047 Tested-by: John Rowley lkml@johnrowley.me Signed-off-by: Nathan Chancellor nathan@kernel.org
drivers/acpi/platform_profile.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
Looks good to me, thanks for fixing this!
Reviewed-by: Sami Tolvanen samitolvanen@google.com
Sami