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 8C24347F2F0; Sat, 12 Sep 2026 13:05:08 +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=1789218310; cv=none; b=g5Ik9///5TgtkgmJWy4xI9vknz3k+zW3SYwgDjjmKdurQU7wPr5Yb/Hlrz2KBxtDsypHjJEg4F9azhl/2zEy3exhfvkklb85GXRDm6Y6YUKAnh370MOnhNLRlgl1jBXbDTZDiRZs1/VKkj6ViOqmZK2mU6iM5sjL0GWYHiB9onw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789218310; c=relaxed/simple; bh=lACm5FWg25/pt8t7M/Itjz1TnSrQKg1V1ENP9Uv6dWc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ns3VeT8vXXzr4ZGji+Uya3UfKLWJqTBmIlmM4/kOd6SuyXzEXpDd0sJcYiziB8g9j2RviNyzce54mOYDi0VoD2r0KQ6usHtaZcM6CIddYvsyC+1ZLd8/Y9oB56KZWNW1qzWRL+1rGT7ptsitTS+YAN7/YHDGwE72uAEeX5hah1U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=B3A0GLg3; 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="B3A0GLg3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2778F1F000FF; Sat, 12 Sep 2026 13:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789218308; bh=XU7ZBgMrVWISKTjYqSZ19plheMp13c4yni3Ye7r/938=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B3A0GLg3ijogPdO2ri53jnF5Kxt10FINIlBkO6e3Ty/pLqiyrcbQlaxYO+UcMDgFU ciTVvgDkkWJ60/BYAN8WFAq1/hrtiafl8hujDYYa1sAk1dV8TH5N2z6UJJDFf9Ebou yd7+cR8lZevfglxrZ87C4Y7KooJ3VVz0WjJj10LE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Phillip Lougher , Yuejie Shi , Andrew Morton , Sasha Levin Subject: [PATCH 6.12 1119/1376] Squashfs: check block offset is not negative Date: Sat, 12 Sep 2026 08:59:05 +0200 Message-ID: <20260912065632.502986040@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: Phillip Lougher [ Upstream commit e300eb5002925b29be803d2661af07266cfa267e ] If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfs_copy_data() to perform an out of bounds access. Fix by checking if offset is negative, and returning 0. This matches existing behaviour where an offset beyond the block returns 0 bytes copied. To trigger this out of bounds access requires a crafted Squashfs filesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be able to mount such a filesystem, but once mounted, an unprivileged user can trigger the out of bounds access by reading the crafted file with the negative offset. Link: https://lore.kernel.org/20260807162951.672510-1-phillip@squashfs.org.uk Fixes: f400e12656ab ("Squashfs: cache operations") Signed-off-by: Phillip Lougher Reported-by: Yuejie Shi Closes: https://lore.kernel.org/all/20260803032735.81785-1-syjcnss@gmail.com/ Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/squashfs/cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c index 25bf038b880ab..2091af7416327 100644 --- a/fs/squashfs/cache.c +++ b/fs/squashfs/cache.c @@ -295,7 +295,7 @@ int squashfs_copy_data(void *buffer, struct squashfs_cache_entry *entry, { int remaining = length; - if (length == 0) + if (length == 0 || offset < 0) return 0; else if (buffer == NULL) return min(length, entry->length - offset); -- 2.53.0