Patch "x86/intel_rdt/cqm: Prevent use after free" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/intel_rdt/cqm: Prevent use after free

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-intel_rdt-cqm-prevent-use-after-free.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d47924417319e3b6a728c0b690f183e75bc2a702 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 16 Jan 2018 19:59:59 +0100
Subject: x86/intel_rdt/cqm: Prevent use after free

From: Thomas Gleixner <tglx@linutronix.de>

commit d47924417319e3b6a728c0b690f183e75bc2a702 upstream.

intel_rdt_iffline_cpu() -> domain_remove_cpu() frees memory first and then
proceeds accessing it.

 BUG: KASAN: use-after-free in find_first_bit+0x1f/0x80
 Read of size 8 at addr ffff883ff7c1e780 by task cpuhp/31/195
 find_first_bit+0x1f/0x80
 has_busy_rmid+0x47/0x70
 intel_rdt_offline_cpu+0x4b4/0x510

 Freed by task 195:
 kfree+0x94/0x1a0
 intel_rdt_offline_cpu+0x17d/0x510

Do the teardown first and then free memory.

Fixes: 24247aeeabe9 ("x86/intel_rdt/cqm: Improve limbo list processing")
Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Peter Zilstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "Roderick W. Smith" <rod.smith@canonical.com>
Cc: 1733662@bugs.launchpad.net
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801161957510.2366@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/cpu/intel_rdt.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -525,10 +525,6 @@ static void domain_remove_cpu(int cpu, s
 		 */
 		if (static_branch_unlikely(&rdt_mon_enable_key))
 			rmdir_mondata_subdir_allrdtgrp(r, d->id);
-		kfree(d->ctrl_val);
-		kfree(d->rmid_busy_llc);
-		kfree(d->mbm_total);
-		kfree(d->mbm_local);
 		list_del(&d->list);
 		if (is_mbm_enabled())
 			cancel_delayed_work(&d->mbm_over);
@@ -545,6 +541,10 @@ static void domain_remove_cpu(int cpu, s
 			cancel_delayed_work(&d->cqm_limbo);
 		}
 
+		kfree(d->ctrl_val);
+		kfree(d->rmid_busy_llc);
+		kfree(d->mbm_total);
+		kfree(d->mbm_local);
 		kfree(d);
 		return;
 	}


Patches currently in stable-queue which might be from tglx@linutronix.de are

queue-4.14/futex-prevent-overflow-by-strengthen-input-validation.patch
queue-4.14/objtool-fix-clang-enum-conversion-warning.patch
queue-4.14/timers-unconditionally-check-deferrable-base.patch
queue-4.14/objtool-improve-error-message-for-bad-file-argument.patch
queue-4.14/futex-avoid-violating-the-10th-rule-of-futex.patch
queue-4.14/objtool-fix-seg-fault-with-gold-linker.patch
queue-4.14/x86-mm-pkeys-fix-fill_sig_info_pkey.patch
queue-4.14/x86-tsc-fix-erroneous-tsc-rate-on-skylake-xeon.patch
queue-4.14/module-add-retpoline-tag-to-vermagic.patch
queue-4.14/x86-kasan-panic-if-there-is-not-enough-memory-to-boot.patch
queue-4.14/x86-idt-mark-idt-tables-__initconst.patch
queue-4.14/x86-retpoline-fill-rsb-on-context-switch-for-affected-cpus.patch
queue-4.14/delayacct-account-blkio-completion-on-the-correct-task.patch
queue-4.14/x86-tsc-future-proof-native_calibrate_tsc.patch
queue-4.14/objtool-fix-seg-fault-with-clang-compiled-objects.patch
queue-4.14/x86-retpoline-add-lfence-to-the-retpoline-rsb-filling-rsb-macros.patch
queue-4.14/x86-cpufeature-move-processor-tracing-out-of-scattered-features.patch
queue-4.14/x86-intel_rdt-cqm-prevent-use-after-free.patch
queue-4.14/objtool-fix-seg-fault-caused-by-missing-parameter.patch