[PATCH 6.1 174/303] fs/resctrl: Fix double-add of pseudo-locked regions RMID to free list

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Reinette Chatre <[email protected]>

[ Upstream commit b9f089723aee892efc77c349ae47a6b452b293c4 ]

A pseudo-locked group's RMID is freed when it is created. On unmount
rmdir_all_sub() unconditionally frees all RMID of all groups, resulting
in a double-free of the pseudo-locked group's RMID. The consequence of this
is that the original free results in the pseudo-locked group's RMID being
added to the rmid_free_lru linked list and the second free then attempts
to add the same RMID entry to the rmid_free_lru again.

Do not double-free a pseudo-locked group's RMID.

Fixes: e0bdfe8e36f3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region")
Signed-off-by: Reinette Chatre <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Cc: <[email protected]>
Link: https://patch.msgid.link/551432dd7e624a862b8e58314c38aaba0afff3e9.1783377598.git.reinette.chatre@intel.com
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2477,10 +2477,6 @@ static void rmdir_all_sub(void)
 		if (rdtgrp == &rdtgroup_default)
 			continue;
 
-		if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
-		    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
-			rdtgroup_pseudo_lock_remove(rdtgrp);
-
 		/*
 		 * Give any CPUs back to the default group. We cannot copy
 		 * cpu_online_mask because a CPU might have executed the
@@ -2489,7 +2485,13 @@ static void rmdir_all_sub(void)
 		cpumask_or(&rdtgroup_default.cpu_mask,
 			   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
 
-		free_rmid(rdtgrp->mon.rmid);
+		if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
+		    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
+			rdtgroup_pseudo_lock_remove(rdtgrp);
+		} else {
+			/* Pseudo-locked group's RMID is freed during setup. */
+			free_rmid(rdtgrp->mon.rmid);
+		}
 
 		kernfs_remove(rdtgrp->kn);
 		list_del(&rdtgrp->rdtgroup_list);