Merge: x86/mce: Make sure to grab mce_sysfs_mutex in set_bank()

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4287

JIRA: https://issues.redhat.com/browse/RHEL-37264  
CVE: CVE-2024-35876  
  
https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=61385231  
Tested: Did sanity mce testing using intel-arrowlake-s-02 system.  
  
commit 3ddf944  
Author: Borislav Petkov (AMD) <bp@alien8.de>  
Date:   Wed Mar 13 14:48:27 2024 +0100  
  
    x86/mce: Make sure to grab mce_sysfs_mutex in set_bank()  
  
    Modifying a MCA bank's MCA_CTL bits which control which error types to  
    be reported is done over  
  
      /sys/devices/system/machinecheck/  
      ├── machinecheck0  
      │   ├── bank0  
      │   ├── bank1  
      │   ├── bank10  
      │   ├── bank11  
      ...  
  
    sysfs nodes by writing the new bit mask of events to enable.  
  
    When the write is accepted, the kernel deletes all current timers and  
    reinits all banks.  
  
    Doing that in parallel can lead to initializing a timer which is already  
    armed and in the timer wheel, i.e., in use already:  
  
      ODEBUG: init active (active state 0) object: ffff888063a28000 object  
      type: timer_list hint: mce_timer_fn+0x0/0x240 arch/x86/kernel/cpu/mce/core.c:2642  
      WARNING: CPU: 0 PID: 8120 at lib/debugobjects.c:514  
      debug_print_object+0x1a0/0x2a0 lib/debugobjects.c:514  
  
    Fix that by grabbing the sysfs mutex as the rest of the MCA sysfs code  
    does.  
  
    Reported by: Yue Sun <samsun1006219@gmail.com>  
    Reported by: xingwei lee <xrivendell7@gmail.com>  
    Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>  
    Cc: <stable@kernel.org>  
    Link: https://lore.kernel.org/r/CAEkJfYNiENwQY8yV1LYJ9LjJs%2Bx_-PqMv98gKig55=2vbzffRw@mail.gmail.com  
  
Signed-off-by: Steve Best <sbest@redhat.com>

Approved-by: David Arcari <darcari@redhat.com>
Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Lucas Zampieri <lzampier@redhat.com>

Author: zampierilucas

arch/x86/kernel/cpu/mce/core.c

@@ -2473,12 +2473,14 @@ static ssize_t set_bank(struct device *s, struct device_attribute *attr,
 		return -EINVAL;
 
 	b = &per_cpu(mce_banks_array, s->id)[bank];
-
 	if (!b->init)
 		return -ENODEV;
 
 	b->ctl = new;
+
+	mutex_lock(&mce_sysfs_mutex);
 	mce_restart();
+	mutex_unlock(&mce_sysfs_mutex);
 
 	return size;
 }