On Tue, Feb 11, 2025 at 3:28 AM 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)
There is no functional issue from the type mismatch because the layout of 'struct kobj_attribute' and 'struct device_attribute' are the same, so the container_of() cast does not break anything aside from CFI.
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 Reviewed-by: Sami Tolvanen samitolvanen@google.com Signed-off-by: Nathan Chancellor nathan@kernel.org
Changes in v3:
- Rebase on 6.14-rc1, which includes updates to the driver to address Greg's previous concerns but this change is still needed for the legacy sysfs interface. v2 can be used for the stable backport.
- Link to v2: https://lore.kernel.org/r/20241118-acpi-platform_profile-fix-cfi-violation-v...
Changes in v2:
- Rebase on linux-pm/acpi
- Pick up Sami's reviewed-by tag
- Adjust wording around why there is no functional issue from the mismatched types
- Link to v1: https://lore.kernel.org/r/20240819-acpi-platform_profile-fix-cfi-violation-v...
drivers/acpi/platform_profile.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c index fc92e43d0fe9..1b6317f759f9 100644 --- a/drivers/acpi/platform_profile.c +++ b/drivers/acpi/platform_profile.c @@ -260,14 +260,14 @@ static int _aggregate_choices(struct device *dev, void *data)
/**
- platform_profile_choices_show - Show the available profile choices for legacy sysfs interface
- @dev: The device
*/
- @kobj: The kobject
- @attr: The attribute
- @buf: The buffer to write to
- Return: The number of bytes written
-static ssize_t platform_profile_choices_show(struct device *dev,
struct device_attribute *attr,+static ssize_t platform_profile_choices_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf){ unsigned long aggregate[BITS_TO_LONGS(PLATFORM_PROFILE_LAST)]; @@ -333,14 +333,14 @@ static int _store_and_notify(struct device *dev, void *data)
/**
- platform_profile_show - Show the current profile for legacy sysfs interface
- @dev: The device
*/
- @kobj: The kobject
- @attr: The attribute
- @buf: The buffer to write to
- Return: The number of bytes written
-static ssize_t platform_profile_show(struct device *dev,
struct device_attribute *attr,+static ssize_t platform_profile_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf){ enum platform_profile_option profile = PLATFORM_PROFILE_LAST; @@ -362,15 +362,15 @@ static ssize_t platform_profile_show(struct device *dev,
/**
- platform_profile_store - Set the profile for legacy sysfs interface
- @dev: The device
*/
- @kobj: The kobject
- @attr: The attribute
- @buf: The buffer to read from
- @count: The number of bytes to read
- Return: The number of bytes read
-static ssize_t platform_profile_store(struct device *dev,
struct device_attribute *attr,+static ssize_t platform_profile_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count){ unsigned long choices[BITS_TO_LONGS(PLATFORM_PROFILE_LAST)]; @@ -401,12 +401,12 @@ static ssize_t platform_profile_store(struct device *dev, return count; }
-static DEVICE_ATTR_RO(platform_profile_choices); -static DEVICE_ATTR_RW(platform_profile); +static struct kobj_attribute attr_platform_profile_choices = __ATTR_RO(platform_profile_choices); +static struct kobj_attribute attr_platform_profile = __ATTR_RW(platform_profile);
static struct attribute *platform_profile_attrs[] = {
&dev_attr_platform_profile_choices.attr,&dev_attr_platform_profile.attr,
&attr_platform_profile_choices.attr,&attr_platform_profile.attr, NULL};
Applied as 6.15 material with some edits in the changelog, thanks!