From 929e4b35023634b421605211c4e1c59b245edd3a Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 16 Jan 2018 19:59:59 +0100 Subject: [PATCH] x86/intel_rdt/cqm: Prevent use after free 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 Signed-off-by: Thomas Gleixner Cc: Ravi Shankar Cc: Peter Zilstra Cc: Stephane Eranian Cc: Vikas Shivappa Cc: Andi Kleen Cc: "Roderick W. Smith" Cc: 1733662@bugs.launchpad.net Cc: Fenghua Yu Cc: Tony Luck Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801161957510.2366@nanos Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/intel_rdt.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c index 88dcf84..9944237 100644 --- 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, struct rdt_resource *r) */ 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, struct rdt_resource *r) 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; } -- 2.7.4