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 6181313C9C4 for ; Wed, 26 Aug 2026 14:41:40 +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=1787755301; cv=none; b=l0VBAHA3RUanqzB9oYayKCZXmj9tTouPlEhKGjC2nBkOalEDkxRn5WPXGw69jrga4LSFmnm7MnMJlkroDTkio6PC/hb39h/JaAiG29gasyU8CpqnFwKUmqGpe2fMSZ+VKkJBTmipB8wLc9NP+qBQ5mjVWUthdFSxp1xT9VaWkQs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787755301; c=relaxed/simple; bh=cME07bScTrcJyaFO5DC63Iv+Xb57Z8cZpEgJz1nn4ZY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=pSgbLfvoIIulxzDqprFLoTeu75+okjuvAHUTl8DViDYC/XS4tRojXvtTXYrId7Ok5s2IfY8LZL+qOtSG/8uqy3xeq9BRwOmTFbnu25c3dRb42saqiSk93E/Mvb/bvcMQ+tej9edC1TavbvPqLGR6F7yTLLFqqNa6USgG6UBYtVc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FuT6jUQC; 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="FuT6jUQC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD1B01F000E9; Wed, 26 Aug 2026 14:41:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787755300; bh=QT+krZYj57401p0RUlI1PIbH+KK8zbW9A7aDpa4q2Ds=; h=From:To:Cc:Subject:Date:Reply-To; b=FuT6jUQChiCOIdf/LWaBwUAS5ynk4dml4O9I1RUGRRdDuhikPd1zp4CBKLhkXC5eI Tz6RnsYfz4GNSBK05BdUYQzyYOrr1i7J0K95RVgUs5se1lFFX0Vv/xEnVNE7T0+XGS dntLu4/9GVgiOZ+j1EHx0TCf93pYk6wB1kH9hrhs= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80578: fbdev: core: Fix pointer desynchronization in fb_io_read() Date: Wed, 26 Aug 2026 16:38:14 +0200 Message-ID: <2026082614-CVE-2026-80578-dcae@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3388; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=L3+RQzuJwh9KWanHdE63EIuXcWKa8C9ETIAhNSrcy0o=; b=owGbwMvMwCRo6H6F97bub03G02pJDFl9v6SCPp59v7RQYvetTxe6PxTEXV1UGHi7VNho+y77V ElehSnLO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAin8oZFtx8wJik+u7e2hvi B1doy3RmmMt8EWWYp6c3p4+7MHC+r8RejytVb+ce5rCdCQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: fbdev: core: Fix pointer desynchronization in fb_io_read() In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to a faulty user buffer), the loop adjusts the chunk size 'c' and updates the remaining 'count'. However, the hardware 'src' pointer has already been eagerly advanced by the original chunk size. If the loop is allowed to continue, the read will resume from an incorrect, over-advanced offset. Since the remaining 'count' was only decremented by the successful bytes, this desynchronization causes the next iterations to execute more hardware reads than originally bounded, eventually leading to out-of-bounds I/O reads. Fix this by breaking out of the loop immediately upon a partial copy_to_user(). A partial copy indicates a faulty user buffer, making subsequent read attempts futile. Breaking out ensures we return the number of successfully read bytes without risking out-of-bounds hardware accesses in subsequent mismatched iterations. The Linux kernel CVE team has assigned CVE-2026-80578 to this issue. Affected and fixed versions =========================== Issue introduced in 6.5 with commit 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff and fixed in 6.6.153 with commit 42bc07b4e5a3c8a02a433388f562a8f46d093e11 Issue introduced in 6.5 with commit 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff and fixed in 6.12.105 with commit 42a6d8126c194133eafab2b0fd5c8668ebfcba5b Issue introduced in 6.5 with commit 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff and fixed in 6.18.46 with commit 7ff87a01ae3a8cd0208f7499386998223a8b5dba Issue introduced in 6.5 with commit 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff and fixed in 7.1.10 with commit 7110b7b794a2aac2c5cf8eb06ebf2af724c74d50 Issue introduced in 6.5 with commit 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff and fixed in 7.2 with commit 81cc73be40c6f028f1ee3f438ace46afe666dbae Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-80578 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: drivers/video/fbdev/core/fb_io_fops.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/42bc07b4e5a3c8a02a433388f562a8f46d093e11 https://git.kernel.org/stable/c/42a6d8126c194133eafab2b0fd5c8668ebfcba5b https://git.kernel.org/stable/c/7ff87a01ae3a8cd0208f7499386998223a8b5dba https://git.kernel.org/stable/c/7110b7b794a2aac2c5cf8eb06ebf2af724c74d50 https://git.kernel.org/stable/c/81cc73be40c6f028f1ee3f438ace46afe666dbae