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 211703176FD; Tue, 17 Mar 2026 17:19:35 +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=1773767975; cv=none; b=uuYI8fHtnGBTzUh/VrIdP5LZmAlqJuyVb45MCSY7rgmJoV4QR88pHjgHeN0YBgwp5Zq3cpBvFOzUaC7W/4n/YkPitPbOzIOEJNstv6svTJDBbTtB2/CpxSsqt3Tyh4qd2ROwYb/n3HQYcWuMOxtOESQsmEdWpWloTzX1RffCcWc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773767975; c=relaxed/simple; bh=eWyE34w6F/XiCCRTWGN79RcvU+skf7lE/aMpnErSGJs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RlwZXzxu6tSZMsQJ+iUo/T2UsTcCEtbo2viQREXqO11Vr2w7+MHs64OeLLf2HDrD/o03U/sq7QPt4SPVLTh/7UOHKJ0DjLQefZnr246rusEtQjiSv1DDRBWT9tl1QBlkzLO8/qQ02iFsCnzB0+duWbaboiD4gI4+Z1UX5YP2oLc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sJfATFyM; 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="sJfATFyM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BA60C4CEF7; Tue, 17 Mar 2026 17:19:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773767975; bh=eWyE34w6F/XiCCRTWGN79RcvU+skf7lE/aMpnErSGJs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sJfATFyMkBFyU96AKmlwcBaFKlziUm6j8fhwPf1Zh0d1Q9AUYu+dhwy1rKLWj/PPJ Xwv8e/CFQgr7oOsm4TD4EAdAxp3RGQ+ioLYRCa/v6/XRbJzepalAJdCKYhwIQU21Gx KaetJJzEtceUOcEGpRzT9uYDfGDkXrEfONjGO8tg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Viktor Malik , Qiao Zhao , Venkat Rao Bagalkote , Saket Kumar Bhaskar , Madhavan Srinivasan , Sasha Levin Subject: [PATCH 6.18 176/333] powerpc, perf: Check that current->mm is alive before getting user callchain Date: Tue, 17 Mar 2026 17:33:25 +0100 Message-ID: <20260317163005.883312948@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317162959.345812316@linuxfoundation.org> References: <20260317162959.345812316@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Viktor Malik [ Upstream commit e9bbfb4bfa86c6b5515b868d6982ac60505d7e39 ] It may happen that mm is already released, which leads to kernel panic. This adds the NULL check for current->mm, similarly to commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain"). I was getting this panic when running a profiling BPF program (profile.py from bcc-tools): [26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0) [26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588 [26215.051952] Faulting instruction address: 0xc00000000020fac0 [26215.051957] Oops: Kernel access of bad area, sig: 11 [#1] [...] [26215.052049] Call Trace: [26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable) [26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30 [26215.052057] [c000000061da6de0] [c0000000005ab2a0] get_perf_callchain+0x100/0x360 [26215.052063] [c000000061da6e70] [c000000000573bc8] bpf_get_stackid+0x88/0xf0 [26215.052067] [c000000061da6ea0] [c008000000042258] bpf_prog_16d4ab9ab662f669_do_perf_event+0xf8/0x274 [...] In addition, move storing the top-level stack entry to generic perf_callchain_user to make sure the top-evel entry is always captured, even if current->mm is NULL. Fixes: 20002ded4d93 ("perf_counter: powerpc: Add callchain support") Signed-off-by: Viktor Malik Tested-by: Qiao Zhao Tested-by: Venkat Rao Bagalkote Reviewed-by: Saket Kumar Bhaskar [Maddy: fixed message to avoid checkpatch format style error] Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260309144045.169427-1-vmalik@redhat.com Signed-off-by: Sasha Levin --- arch/powerpc/perf/callchain.c | 5 +++++ arch/powerpc/perf/callchain_32.c | 1 - arch/powerpc/perf/callchain_64.c | 1 - 3 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c index 26aa26482c9ac..992cc5c982144 100644 --- a/arch/powerpc/perf/callchain.c +++ b/arch/powerpc/perf/callchain.c @@ -103,6 +103,11 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + perf_callchain_store(entry, perf_arch_instruction_pointer(regs)); + + if (!current->mm) + return; + if (!is_32bit_task()) perf_callchain_user_64(entry, regs); else diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c index ddcc2d8aa64a5..0de21c5d272c2 100644 --- a/arch/powerpc/perf/callchain_32.c +++ b/arch/powerpc/perf/callchain_32.c @@ -142,7 +142,6 @@ void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry, next_ip = perf_arch_instruction_pointer(regs); lr = regs->link; sp = regs->gpr[1]; - perf_callchain_store(entry, next_ip); while (entry->nr < entry->max_stack) { fp = (unsigned int __user *) (unsigned long) sp; diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c index 115d1c105e8a8..30fb61c5f0cb0 100644 --- a/arch/powerpc/perf/callchain_64.c +++ b/arch/powerpc/perf/callchain_64.c @@ -77,7 +77,6 @@ void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, next_ip = perf_arch_instruction_pointer(regs); lr = regs->link; sp = regs->gpr[1]; - perf_callchain_store(entry, next_ip); while (entry->nr < entry->max_stack) { fp = (unsigned long __user *) sp; -- 2.51.0