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 2D2311946C8; Fri, 9 Jan 2026 12:02:38 +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=1767960158; cv=none; b=NNqZIyXnQiZmaGoR3NOfgBymdeajVV4S8Ck9CD3sQhfC3VK5t6zToGY4fG4nUo4g3GqZnjPziBosKPb5RASvXGglz9QsOs911Y4ACy0YEYAZ4EVpSiBRV7z5jt4bAr9UfVeOR+F/lGhzcepbu7mQAKJhXStbT8cBXbeWdsTznRE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767960158; c=relaxed/simple; bh=t0nfZyK4uLsKMLdV/Iy1qyhNpe2gLS208NjF9YykYp8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kMYMhXCnGFhwRXkQnWds/TOM9Xz47o085/1bCw0ZLwhY9hMLqI1tHiOCxVKM7SRjWSN6Ykgk68nh6a0Nsvmayu8znnEi2XRjpIWSKp2clRY5HsKQ/1qKr+ODcwo/5CwtMRSr7aLlFGiOe636ZCnzWbTDWLAi+jbCZZUQcpAWx8k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=L5VbHEdP; 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="L5VbHEdP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC4A9C4CEF1; Fri, 9 Jan 2026 12:02:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767960158; bh=t0nfZyK4uLsKMLdV/Iy1qyhNpe2gLS208NjF9YykYp8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L5VbHEdP6ngqc08dU/Dgrxu9p85x+EFqghMQeHpC0+WCbBLCbwhlhrsvexlNta6Mq kOtMMtr6o1+jnpO56sWrsYTAN+KPXnM82RilYUbic5IQush+pXttzI9692dSXoQ8wL lxAxIacVfVw3htD818hai/Q2hoi+/Eo1M+ZL2VMw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzkaller , George Kennedy , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 6.6 305/737] perf/x86/amd: Check event before enable to avoid GPF Date: Fri, 9 Jan 2026 12:37:24 +0100 Message-ID: <20260109112145.479378203@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112133.973195406@linuxfoundation.org> References: <20260109112133.973195406@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: George Kennedy [ Upstream commit 866cf36bfee4fba6a492d2dcc5133f857e3446b0 ] On AMD machines cpuc->events[idx] can become NULL in a subtle race condition with NMI->throttle->x86_pmu_stop(). Check event for NULL in amd_pmu_enable_all() before enable to avoid a GPF. This appears to be an AMD only issue. Syzkaller reported a GPF in amd_pmu_enable_all. INFO: NMI handler (perf_event_nmi_handler) took too long to run: 13.143 msecs Oops: general protection fault, probably for non-canonical address 0xdffffc0000000034: 0000 PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000001a0-0x00000000000001a7] CPU: 0 UID: 0 PID: 328415 Comm: repro_36674776 Not tainted 6.12.0-rc1-syzk RIP: 0010:x86_pmu_enable_event (arch/x86/events/perf_event.h:1195 arch/x86/events/core.c:1430) RSP: 0018:ffff888118009d60 EFLAGS: 00010012 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000034 RSI: 0000000000000000 RDI: 00000000000001a0 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: ffff88811802a440 R14: ffff88811802a240 R15: ffff8881132d8601 FS: 00007f097dfaa700(0000) GS:ffff888118000000(0000) GS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200001c0 CR3: 0000000103d56000 CR4: 00000000000006f0 Call Trace: amd_pmu_enable_all (arch/x86/events/amd/core.c:760 (discriminator 2)) x86_pmu_enable (arch/x86/events/core.c:1360) event_sched_out (kernel/events/core.c:1191 kernel/events/core.c:1186 kernel/events/core.c:2346) __perf_remove_from_context (kernel/events/core.c:2435) event_function (kernel/events/core.c:259) remote_function (kernel/events/core.c:92 (discriminator 1) kernel/events/core.c:72 (discriminator 1)) __flush_smp_call_function_queue (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/csd.h:64 kernel/smp.c:135 kernel/smp.c:540) __sysvec_call_function_single (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./arch/x86/include/asm/trace/irq_vectors.h:99 arch/x86/kernel/smp.c:272) sysvec_call_function_single (arch/x86/kernel/smp.c:266 (discriminator 47) arch/x86/kernel/smp.c:266 (discriminator 47)) Reported-by: syzkaller Signed-off-by: George Kennedy Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Sasha Levin --- arch/x86/events/amd/core.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index aa8fc2cf1bde7..211f429750f5f 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -745,7 +745,12 @@ static void amd_pmu_enable_all(int added) if (!test_bit(idx, cpuc->active_mask)) continue; - amd_pmu_enable_event(cpuc->events[idx]); + /* + * FIXME: cpuc->events[idx] can become NULL in a subtle race + * condition with NMI->throttle->x86_pmu_stop(). + */ + if (cpuc->events[idx]) + amd_pmu_enable_event(cpuc->events[idx]); } } -- 2.51.0