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HID: amd_sfh: Serialize access to the shared emp2 pointer

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The SFH accessors reach the device through a file-global emp2 pointer
that is published at probe and cleared on remove. amd_get_sfh_info() is
exported and called from other modules on unrelated threads, so a reader
can observe a non-NULL emp2 and then race a concurrent unbind that clears
it and frees the device.

Serialize the emp2 publish/clear and all readers under a mutex, so a
reader either sees a live device for the whole access or sees NULL.

Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
This commit is contained in:
Basavaraj Natikar 2026-08-03 23:22:27 +05:30 committed by Jiri Kosina
parent 1a73a4e767
commit c57016bcf6
1 changed files with 6 additions and 0 deletions
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6
drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_interface.c
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@ -8,12 +8,14 @@
* Author: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
*/
#include <linux/amd-pmf-io.h>
#include <linux/cleanup.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/iopoll.h>
#include "amd_sfh_interface.h"
static struct amd_mp2_dev *emp2;
static DEFINE_MUTEX(emp2_lock);
static int amd_sfh_wait_response(struct amd_mp2_dev *mp2, u8 sid, u32 cmd_id)
{
@ -78,12 +80,14 @@ static struct amd_mp2_ops amd_sfh_ops = {
void sfh_deinit_emp2(void)
{
guard(mutex)(&emp2_lock);
emp2 = NULL;
}
void sfh_interface_init(struct amd_mp2_dev *mp2)
{
mp2->mp2_ops = &amd_sfh_ops;
guard(mutex)(&emp2_lock);
emp2 = mp2;
}
@ -160,6 +164,8 @@ static int amd_sfh_als_info(u32 *ambient_light)
int amd_get_sfh_info(struct amd_sfh_info *sfh_info, enum sfh_message_type op)
{
guard(mutex)(&emp2_lock);
if (sfh_info) {
switch (op) {
case MT_HPD: