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 C69B33CF698 for ; Fri, 11 Sep 2026 02:20:13 +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=1789093215; cv=none; b=oUqBraJs85v6qFFdlRKJ2DBYO8dlFdAODOJTC0WiMFS6ElTRCIY/cSDiLrdHiXeHZKyCyk/XqD/boQJZt09ySHwVLE8oPbbxOoLSxsmlGaVZh0Xq0AeHEKy6GUCCrYRuFG+6D7GiL4Xkrlf7u6AwZRXwxaWXnxMkrzJw6qQhJ0Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789093215; c=relaxed/simple; bh=jgFIa31waZKo4ePRUgWArCHnqOoKapTM2eo+ZmkuOOI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YOpJx/T0sgN1xieb7FBaGzbxuRb1qB9PXjjSBfNVdJ9t5olcUaQX/qsGW4g2hPegwK26lYK+HUgfBDXBSqs0Qsu8c7UXBYrGu+CK4VAXu2dkQ012lYYC/zFzFzm4ENa4Q6XX3Qzcr5zk2YGnIxpLCMTrlEHYavhu4vA9P5SXVZ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mgt7DFvd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mgt7DFvd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2DEC1F00893; Fri, 11 Sep 2026 02:20:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789093213; bh=BYIKteZuQAJNen7OvbX9ucRSrjc6OfnAcL8/eZJfwbI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Mgt7DFvdolV1BYRl7/o9cM2SCB9QahOA/UJX6dcivpooXlA5Kubgpb8uzos80vVlP 0RgRGeTDDCg33r6UWYsi9qGPy3oIyv0q1eED91Fyp4hAlcDxFrfxrWCrtRwUikNUDC lMUgGLOLEiOK63k/e9Xlt1N+o/IfwGFqGje57CiF4uhbfvtzbez2GyPQlQjmdcoq/x 6CLS1YCjaWlyE6fe5bzL0sT7rjaIkFHLiKKl2xCJlR+14V64+Sv46JWp5KBrCxS+3h zQQggYzNqAKvcgAovQuyUSaOtqBs8K9ha1oPgSeZNqzyGZJSA75mdrrq53JSzoJbbg UxpdwVJasBhiw== From: Sasha Levin To: stable@vger.kernel.org Cc: Jinjie Ruan , Sourabh Jain , Madhavan Srinivasan , Sasha Levin Subject: [PATCH 5.15.y 2/2] powerpc/kexec_file: Prevent kexec range truncation Date: Thu, 10 Sep 2026 22:20:10 -0400 Message-ID: <20260911022010.51146-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260911022010.51146-1-sashal@kernel.org> References: <2026090925-sliceable-cold-552f@gregkh> <20260911022010.51146-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jinjie Ruan [ Upstream commit fa40f9dbdd4af53e7445d9135b5b207eb8adf372 ] 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: Sasha Levin --- arch/powerpc/kexec/ranges.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c index 4a3ac17263c8c..975b522f0d6aa 100644 --- a/arch/powerpc/kexec/ranges.c +++ b/arch/powerpc/kexec/ranges.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -103,19 +104,16 @@ static void __merge_memory_ranges(struct crash_mem *mem_rngs) struct crash_mem_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]; } } -- 2.53.0