From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2ED5C3AD536; Mon, 23 Mar 2026 13:59:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274389; cv=none; b=L8SniBwrTj2hTtQ7LrpZ7ZGCekHfTonqLPxX1Zh74gq+TENUA5FwRj2OM1gLLLCNRBMT57WupZ+r9j82dJcSZ3sTJJN4p3t0QZCXD+AHoxWmyfQ6pbn4HabqTyzPqwJlnGw3XXJrxMHYKMz1qJPi9IdTEwiz488x7rTzRCDjk8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274389; c=relaxed/simple; bh=+CHolI0OoLHZYDLufhHM5SNrDl3HwUgcGhgXG0Fngac=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CbwBJDZZ3WNUIfkMouMR8auAnEl08yRu1HZu+REPuFLL+wfSWwdRgiRgoXDVRqA3aRQZPcoCdOknY9j+dVhfVNdrC6Fl+53j/vrnPK4fdusfhOOrXmGmr+rxjg8UtBq+FwNpxf5HFUtCZrYL/2WJKtaNALzClAvD4ATX1QgTDes= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2N8x75LR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2N8x75LR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A514DC2BCB6; Mon, 23 Mar 2026 13:59:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774274389; bh=+CHolI0OoLHZYDLufhHM5SNrDl3HwUgcGhgXG0Fngac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2N8x75LR5HjX8X2SaFhO2KaBYa98EdQdmX0BHHBA545j5amGq1luLqq3hcm9BiabJ kQ+Up8lWxx/0JJ99L3v1nqdfX8YPFhyNOi3hAmp2wpJkKgrEA9M5AAWcmg3w5LsdSi hBBHziu7NE/pkjJwnL6op2clazma7xWupSz8rvR8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ben Horgan , James Morse , Will Deacon , Sasha Levin Subject: [PATCH 6.19 201/220] arm_mpam: Fix null pointer dereference when restoring bandwidth counters Date: Mon, 23 Mar 2026 14:46:18 +0100 Message-ID: <20260323134510.923477284@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134504.575022936@linuxfoundation.org> References: <20260323134504.575022936@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Horgan [ Upstream commit 4ad79c874e53ebb7fe3b8ae7ac6c858a2121f415 ] When an MSC supporting memory bandwidth monitoring is brought offline and then online, mpam_restore_mbwu_state() calls __ris_msmon_read() via ipi to restore the configuration of the bandwidth counters. It doesn't care about the value read, mbwu_arg.val, and doesn't set it leading to a null pointer dereference when __ris_msmon_read() adds to it. This results in a kernel oops with a call trace such as: Call trace: __ris_msmon_read+0x19c/0x64c (P) mpam_restore_mbwu_state+0xa0/0xe8 smp_call_on_cpu_callback+0x1c/0x38 process_one_work+0x154/0x4b4 worker_thread+0x188/0x310 kthread+0x11c/0x130 ret_from_fork+0x10/0x20 Provide a local variable for val to avoid __ris_msmon_read() dereferencing a null pointer when adding to val. Fixes: 41e8a14950e1 ("arm_mpam: Track bandwidth counter state for power management") Signed-off-by: Ben Horgan Reviewed-by: James Morse Signed-off-by: James Morse Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- drivers/resctrl/mpam_devices.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index b495d52918681..41fe421171813 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -1428,6 +1428,7 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 partid, static int mpam_restore_mbwu_state(void *_ris) { int i; + u64 val; struct mon_read mwbu_arg; struct mpam_msc_ris *ris = _ris; struct mpam_class *class = ris->vmsc->comp->class; @@ -1437,6 +1438,7 @@ static int mpam_restore_mbwu_state(void *_ris) mwbu_arg.ris = ris; mwbu_arg.ctx = &ris->mbwu_state[i].cfg; mwbu_arg.type = mpam_msmon_choose_counter(class); + mwbu_arg.val = &val; __ris_msmon_read(&mwbu_arg); } -- 2.51.0