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 E848B585985 for ; Fri, 11 Sep 2026 20:00:11 +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=1789156823; cv=none; b=IAS0P7ex4J3iL9jEbhjP4CcrybjVzgrocGtWSS1tK3W69487L8Y1rnbjw8fqYI39ATUpqmt59/PzLgkvGfVibSEjGYQfcwiuhOdDkEYKkKX9q62fM7SSVBtgOMBmXfT+pcg88ZYhCxSaeVRVrovGQ3AvcIXTBy7eXF76hmtN9rU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156823; c=relaxed/simple; bh=AccGIDhKt/fV+QnIHRIuMNOVzXWIywOXUuVYQ7f4XT0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ZcfvP3Wl+WLDZjaaRokKd01jiyioSLsh422y7E7/VZzkNqeSoHbnzj1ZaLQ3veXEn5oI/JK4UCbyox2A4ufqgqz/7+Osv/W5gZLJGdiiLoK6xIyvzP+bZOj/fI51fkLxE1DN5Zlw9L0A5YLswcI8YlsLuFh8RCzmGP4hgrHsw/c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xtrz8QEy; 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="xtrz8QEy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D92B1F00898; Fri, 11 Sep 2026 20:00:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156809; bh=OMnZMGPVwa/MRk2E76uqmmvyLAvXozgiJCPwUQhdQbs=; h=From:To:Cc:Subject:Date:Reply-To; b=xtrz8QEyRU4Ru8prHV5BMdDvQwzIkzQyiIIGSUdx2QiIp9CFbIrOFwC07uiHaOYZh FqX/g53GJQ3lyGTOzQ5K05vJdFxVpPZUdBCfRFgyp/K7HhLR68FH/6Z3hHPIwuVkhB ZNaX7/31NG3V6SFRzXq3tZYMeVLpBLK3PpvTI+Zg= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89641: cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size() Date: Fri, 11 Sep 2026 21:45:30 +0200 Message-ID: <2026091142-CVE-2026-89641-4c69@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=2985; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=DBW2uBDnQU716EE9z5eny6U/IcU6VQfVNVX3y4rbn44=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIssucM0QmfhV1cpcRcjhZsKkx73JSxpsHX+eCEqxb Z1tcq6vI5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACayxZ9hnvnsZUu9979+KfZw j9/+6Wvq/5Zv8WFYsNST9Rfr3538uxl/OxoYeAvvbD4UAgA= 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: cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size() When the else branch of cifs_file_set_size() finds a writable file handle via find_writable_file(), it borrows tcon and server from the handle's tlink, attempts the handle-based set_file_size() RPC, and then releases the handle with cifsFileInfo_put(). If set_file_size() fails, execution falls through to the path-based fallback, which reuses the borrowed tcon and server under the "if (tcon == NULL)" guard. Since tcon is not NULL at that point, the guard is skipped. If cifsFileInfo_put() dropped the last reference on a tlink that was already removed from the tlink tree (TCON_LINK_IN_TREE cleared, as happens during reconnection or session teardown), cifs_put_tlink() will have freed tcon; the subsequent set_path_size() call is then a use-after-free. Setting tcon = NULL after cifsFileInfo_put() causes the existing guard to take the cifs_sb_tlink() path, which acquires a fresh reference for the path-based operation or fails cleanly if the session is gone. The Linux kernel CVE team has assigned CVE-2026-89641 to this issue. Affected and fixed versions =========================== Issue introduced in 6.18 with commit 110fee6b9bb58a5c50047fc2594d415f741b591e and fixed in 6.18.50 with commit 4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4 Issue introduced in 6.18 with commit 110fee6b9bb58a5c50047fc2594d415f741b591e and fixed in 7.2.4 with commit 4bea15d9c7683218f57b8c1f5f0aa75cab76af8d Issue introduced in 6.18 with commit 110fee6b9bb58a5c50047fc2594d415f741b591e and fixed in 7.3-rc1 with commit b96db32fed8dfb2478d7c208f89bf383beed1535 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-2026-89641 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: fs/smb/client/inode.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/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4 https://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d https://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535