From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2B19F47A0B0; Sat, 12 Sep 2026 11:45:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213527; cv=none; b=XNVcAdfI/D2gB7mh9GJvAmwWvWoY8SLD5FHt8Bo4e3qnmFOdzuwq2NDjJAzUp8d2mI+DnWoH/IMPD/uu2bEP120ozkj4A4bJemPvy0aRO2WpvYXnqCiKXPsnu41cb529Su/QnuojbW1k125RN06TnIqaxMTvINX1BwMQJsEwAEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213527; c=relaxed/simple; bh=wl3WDobWlNBAAiSW+GeLlFV9QYsTyfwJwWQaWQ0r76I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=X4y/5ypT9WA/l46G+51JpY2usDmqIvezEENjREFuEvI8J2QaJbs4kR/ZEcIVQXps3djWTJeogoA/UoAvQAvbyXfvtXAYwPomVF0Hgcf3nny70+/dNncogImyP4qAOrfiX93df6PMgOOnE45iSnGe5sRoyKp8nmOW6g52DuYzv1k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=R1QYjPZQ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="R1QYjPZQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21A1B1F000FF; Sat, 12 Sep 2026 11:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789213521; bh=iq51sC/2IBGvc3ty7QdlrSqjfH+G8HuSXzmO3gU6100=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=R1QYjPZQ2da0xCXYvYh/itwsCEF+QLja0KoAmolxlq8hulxYi1r7nzANfMRDXjVac hFI//tRHe8D5BsUHYgVZnJz7EHbgP0PUXsCUG7y3g0ZbW6eWe+hA/3LxNg8MVLjlqm FGrIqP33tNyV5281XmmA0jB/FUCOW2L/Do8aWfuc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jinjie Ruan , Sourabh Jain , Madhavan Srinivasan Subject: [PATCH 6.12 0096/1376] powerpc/kexec_file: Prevent kexec range truncation Date: Sat, 12 Sep 2026 08:42:02 +0200 Message-ID: <20260912065609.700137100@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jinjie Ruan commit fa40f9dbdd4af53e7445d9135b5b207eb8adf372 upstream. Sashiko AI review pointed out the following issue. The __merge_memory_ranges() function incorrectly handles overlapping memory ranges when merging them. Although sort_memory_ranges() sorts all ranges by their start address in ascending order beforehand, the merge logic remains defective in two ways: 1. It compares the current range's start against the previous element (i-1) instead of the running target index (idx) 2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'. This logic flaw leads to critical memory truncation when a larger memory range completely subsumes subsequent smaller ranges. For example, consider a sorted input array with three ranges: Range A (idx=0): [0x1000 - 0x9000] Range B (i=1): [0x2000 - 0x5000] (completely inside Range A) Range C (i=2): [0x6000 - 0x8000] (completely inside Range A) 1. When i=1 (Range B): ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE. The code executes: ranges[0].end = ranges[1].end, which erroneously shrinks Range A's end from 0x9000 down to 0x5000. 2. When i=2 (Range C): ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE. The code falls into the else block, creating a broken new range. As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000] are completely lost from the kexec exclude lists, potentially allowing the crash kernel to overwrite active memory, causing data corruption or crashes. Fix this by ensuring the start of the current range is compared against the end of the active merged range (idx), and use max() to safely prevent the outer boundary from being truncated. Cc: stable@vger.kernel.org Fixes: 180adfc532a8 ("powerpc/kexec_file: Add helper functions for getting memory ranges") Signed-off-by: Jinjie Ruan Reviewed-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260729012948.2797865-4-ruanjinjie@huawei.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kexec/ranges.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/arch/powerpc/kexec/ranges.c +++ b/arch/powerpc/kexec/ranges.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -105,19 +106,16 @@ static void __merge_memory_ranges(struct struct range *ranges; int i, idx; - if (!mem_rngs) + if (!mem_rngs || mem_rngs->nr_ranges <= 1) return; idx = 0; - ranges = &(mem_rngs->ranges[0]); + ranges = mem_rngs->ranges; for (i = 1; i < mem_rngs->nr_ranges; i++) { - if (ranges[i].start <= (ranges[i-1].end + 1)) - ranges[idx].end = ranges[i].end; + if (ranges[i].start <= (ranges[idx].end + 1)) + ranges[idx].end = max(ranges[idx].end, ranges[i].end); else { idx++; - if (i == idx) - continue; - ranges[idx] = ranges[i]; } }