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 DE67B37B003 for ; Sat, 22 Aug 2026 15:34:50 +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=1787412892; cv=none; b=BYcpCK+JUs/QaGshtG7gdnq6n3tLjGOC/vNbx5NKI9YQUGLn2avLXtrRp/OEZru3xBT64rO19JnJE5bqRdKxZzeS4hsKlUgdPuQSYyiOC1a71LMGb/LVIxyR7kmlpLwh1GonDDEmZSyAbPzbQYSpTztkFxKip+DuknfW5jpcfvA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787412892; c=relaxed/simple; bh=PLuh3vNvD0neJtc4gfjaSStCY+1K/t0RFWoXdACLFl4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=J6ABxipZIVPUMB6d0rFMb/bBTzGQ/fu/1xuYcXlg4X1U6vB11GQnBMuuvq1DGbkbHeBSVvxMNZEED6BHuaOOo30iVY249qNYGSV28+gN3YCg8ufUTfBv1fqlSUGyzt5pi8HxFFeGw7q1cqaILg9xm6Wu7nf4whe50rjPyTDQX4M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IwXPNG3k; 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="IwXPNG3k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A71BE1F000E9; Sat, 22 Aug 2026 15:34:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787412890; bh=hT92qO4r3csn7Fu+ylJw/ydov++fHaMLy8y75EzsHKk=; h=From:To:Cc:Subject:Date:Reply-To; b=IwXPNG3kfEA98Ss4ks1ORucVLpvdAAdg5kyjImL3NlHtg7AX7WdwFZak690TsBQen pJQJoEM2eQJNDOIrj7gIA0OulHz+bcQVJLjODRfGimeARQYCrpatMO/IOAEtl0zHoj qS+thuPK/mhp7D6qtZrcca0d45iQ4fX5URX8nhgs= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74591: mm/filemap: __filemap_add_folio() restore index before retrying Date: Sat, 22 Aug 2026 17:31:15 +0200 Message-ID: <2026082213-CVE-2026-74591-72ed@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=3409; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=fD5iFzqJYd604gTLuxzb2WhJGpDiDxgJhOO7VBJ3erg=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmdBw7qz1RV91l+wLSuMtTMamv8lE9dm5ycm8oW5Vca2 2iVm3J3xLIwCDIxyIopsnzZxnN0f8UhRS9D29Mwc1iZQIYwcHEKwESOzWeYKxJz+5LImcq90/zD cnkvRdw6wOZZxbBg9Z3Ex4rRnWc/6r657J2+MziXP+gJAA== 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: mm/filemap: __filemap_add_folio() restore index before retrying In __filemap_add_folio()'s split-a-conflict loop, xas_set_order() is applied repeatedly: each application modifies xas.xa_index, rounding it down according to the split_order attempted at that stage: and if all goes as intended, it eventually (or immediately) converges on an xas_try_split() to the required folio_order, with xas.xa_index now the same as index: then xas_store() puts the new folio into the xarray there. But if a new node was needed, and GFP_NOWAIT allocation did not get one, the lock is dropped, xas_nomem() used to allocate, and sequence retried. If (that part of) the xarray is unchanged when the lock is reacquired, no problem. But what if the conflict was meanwhile resolved by another thread (perhaps even doing the same thing, inserting a folio at that same index)? Isn't there a danger of now putting our folio into the xarray at an intermediate rounded-down index? With !folio_contains() bug to follow, when CONFIG_DEBUG_VM=y is checking for that. Fix this with an xas_set_order() to restore the original xas.xa_index at the bottom of the loop, so the retry does a full re-evaluation after reacquiring the lock, and cannot reach xas_store() with the wrong index. Production was suffering from rare SIGILLs and SIGSEGVs, executable text found a page away from where it belonged, !folio_contains() bug hit when debug enabled: symptoms not seen since this patch went in. The Linux kernel CVE team has assigned CVE-2026-74591 to this issue. Affected and fixed versions =========================== Issue introduced in 6.15 with commit 200a89c159a7a416115e6e309183c82183bf98aa and fixed in 6.18.45 with commit 4917e3ebcab50f0265e8ca01c8567de4c4a47511 Issue introduced in 6.15 with commit 200a89c159a7a416115e6e309183c82183bf98aa and fixed in 7.1.9 with commit 267ecd2eb7759c26f1a026eb0a5b231071534c9c Issue introduced in 6.15 with commit 200a89c159a7a416115e6e309183c82183bf98aa and fixed in 7.2 with commit 86da3f7e1e609e1e8bfbab198af68467c5a015a5 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-2026-74591 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: mm/filemap.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/4917e3ebcab50f0265e8ca01c8567de4c4a47511 https://git.kernel.org/stable/c/267ecd2eb7759c26f1a026eb0a5b231071534c9c https://git.kernel.org/stable/c/86da3f7e1e609e1e8bfbab198af68467c5a015a5