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 6905E1FC7D8; Sun, 26 Jan 2025 14:56:12 +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=1737903372; cv=none; b=GG7xaoI3CarJnU2fW4Xr7hQxt+Lc80P6+K5qezipDO9DMUtb9nCT/BSZRfY3sBIH1ZwvBN2VmMOZ29mfJtymBtNFvKi/hMZls3nlaF7yAVH+TiI8txdpc7NVcO6RGU87v2XaIdo3OpPaOe7zziNKOJO6n/XeUxT53Dn9tBkRV5o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903372; c=relaxed/simple; bh=eV63UqxWcasLmFKmafSwVGhlsTu3il2siuiSSVmN0AM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kasPlLChhnbmAL0wNlV3yVBkHy8klt6sykvUBFdrv1JFtoNqPQkcdX5Eyi4vJZ156HfW7hDQXc+3aUl+FLAUjPk1nQzfn3u56EukvaVavHV/ub68XOAzI62ehnDjB1Y65U+TyB8oqeVMDmN9c0+PYzExVjCLxpb6S4Vj7TKyV8s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QKU+P6Zz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QKU+P6Zz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 169B6C4CEE2; Sun, 26 Jan 2025 14:56:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903371; bh=eV63UqxWcasLmFKmafSwVGhlsTu3il2siuiSSVmN0AM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QKU+P6Zz5zgUkRsJ9nsKaDYExQVvC/CJGAfHtyEakzM2U17t1PMan/KDeratoH6nC fWKPmcl8qiIGvyVJT+q080lyPdsfPA+XT7XpHynD/vWw3y32csV7D3p16+UUMXmqr8 u1i+XPm3TsARNz72fN5mQ5sueHpea8fnIk2XQurlTBQxqfu2FzvB1Wzy2Qk/NMi3ov z2lXb6SHZ91SzMvAC6HFfPwM+GuhEwAcnrAKG5C5yDgGJRflF7ch072mSWU474ePyd V67Yj4QqNyPpqHofvN40yqNLA+eYTmW5Dv1sHBicI0Vh78uKw+0CMZXFMh2HaDrBUx GD7+UEHKowJhg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jeongjun Park , Steven Rostedt , Sasha Levin , mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 31/31] ring-buffer: Make reading page consistent with the code logic Date: Sun, 26 Jan 2025 09:54:47 -0500 Message-Id: <20250126145448.930220-31-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250126145448.930220-1-sashal@kernel.org> References: <20250126145448.930220-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.12.11 Content-Transfer-Encoding: 8bit From: Jeongjun Park [ Upstream commit 6e31b759b076eebb4184117234f0c4eb9e4bc460 ] In the loop of __rb_map_vma(), the 's' variable is calculated from the same logic that nr_pages is and they both come from nr_subbufs. But the relationship is not obvious and there's a WARN_ON_ONCE() around the 's' variable to make sure it never becomes equal to nr_subbufs within the loop. If that happens, then the code is buggy and needs to be fixed. The 'page' variable is calculated from cpu_buffer->subbuf_ids[s] which is an array of 'nr_subbufs' entries. If the code becomes buggy and 's' becomes equal to or greater than 'nr_subbufs' then this will be an out of bounds hit before the WARN_ON() is triggered and the code exiting safely. Make the 'page' initialization consistent with the code logic and assign it after the out of bounds check. Link: https://lore.kernel.org/20250110162612.13983-1-aha310510@gmail.com Signed-off-by: Jeongjun Park [ sdr: rewrote change log ] Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/ring_buffer.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 703978b2d557d..28fad7bcfcf86 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7059,7 +7059,7 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, } while (p < nr_pages) { - struct page *page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); + struct page *page; int off = 0; if (WARN_ON_ONCE(s >= nr_subbufs)) { @@ -7067,6 +7067,8 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, goto out; } + page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); + for (; off < (1 << (subbuf_order)); off++, page++) { if (p >= nr_pages) break; -- 2.39.5