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 2356A37A854 for ; Sat, 15 Aug 2026 06:29:23 +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=1786775364; cv=none; b=V/z61uFLDow26X3jVp4fhPLI3d4rzWRuRaqNuiXHulzl8x4xNfu1siAoH1HB5uW10jj81FTlJUfWEUBi0Xtmz+f0UQ9wZxKgAMI0AnAQ+uf2SUQiy4UeL8FG/Rtr1eT/suPsodhv1WrD+61xHf2R3lZsYk2zoH8n1HkUxW9u18c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786775364; c=relaxed/simple; bh=8gy9HWNIK1CCXNADp2Lp7fPzrC4Cd/fIpwbmZJQ4nR8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QmXVfiCjKHtpyqKEuxFYfvugQnF50AcPfQK7bgfA1vfdePzC+uJjFvIiQA60E9HP4NSohxDfrnjUDMa3XiRFnAFYURpFfDTJX1E4HzMg22cMax+AU3O2M6+YMYS0G2N29Jocj8oD0EdWIBg+2oQuYLSU/iw27np5PjtpeeJSO6k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vXW85A37; 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="vXW85A37" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 780101F000E9; Sat, 15 Aug 2026 06:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786775363; bh=XPx2WXrLDHEKqCHVS+Gye91JtFxSGJuuraYCw3NZ/Qg=; h=From:To:Cc:Subject:Date:Reply-To; b=vXW85A37S1rEU/dTIa7tJKDQuCpry0rbf29McSm0hHymOVhOjN4L352cztfggN3dP gVbPen7nOFOWHpAux6jkkcmZAcJ0Oj2wyWw1V07m9qCKBbOgt+0QOCm4rMPSaGIMxT 7ra5AzjyA9UEvJafVLFhk8pQair8Uho8ZjFg4s38= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-72422: ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE Date: Sat, 15 Aug 2026 15:08:21 +0900 Message-ID: <2026081525-CVE-2026-72422-a888@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=4905; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=uoTUPjZ8nXIp9GLHKnKx0JiRgBt94kDqbtKqLlZKeqo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNDB9d82fuXH38U0RgyrrufUvW/IxttyrkYeCde13X4 ED9KqWijlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZiIwHuGBe1JuqYz5ap0DU9t Sqr08Vl/ZZWhLMOCDbIHzWZv5My1ket7/lvwIE+BaK8eAA== 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: ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE conn->preauth_info is shared connection state (struct preauth_integrity_info, kmalloc-96) that is allocated and freed by the SMB2 NEGOTIATE handler and read by the response send path. smb2_handle_negotiate() allocates conn->preauth_info, and on a deassemble_neg_contexts() failure kfrees it and sets it to NULL. Both the allocation and the free/NULL happen under ksmbd_conn_lock(conn) (the connection srv_mutex), which is held across the whole handler body. The response send path smb3_preauth_hash_rsp(), called from the send: block of __handle_ksmbd_work(), reads conn->preauth_info and dereferences conn->preauth_info->Preauth_HashValue (via ksmbd_gen_preauth_integrity_hash()) without taking conn_lock. When a client drives two SMB2 NEGOTIATE requests on the same connection, one worker can free conn->preauth_info on the failing-negotiate path while a concurrent send-path worker is reading it, producing a slab use-after-free read (KASAN-confirmed). The send-path read tested conn->preauth_info for NULL but raced with the free that occurs between the NULL check and the dereference, so the NULL guard alone does not close the window. Serialize the NEGOTIATE-branch read in smb3_preauth_hash_rsp() under ksmbd_conn_lock(conn) and re-check conn->preauth_info inside the lock. Because the negotiate handler holds conn_lock across its kfree + NULL assignment, a reader that also takes conn_lock either runs fully before the allocation or fully after the NULL store, and can never observe the freed-but-not-yet-NULLed pointer. ksmbd_gen_preauth_integrity_hash() takes no locks itself (it only computes a SHA-512 over the buffer), so no lock-ordering inversion is introduced, and conn_lock is a sleepable mutex which is safe on this send path (it already performs network I/O). The Linux kernel CVE team has assigned CVE-2026-72422 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15.61 with commit dd4e4c811898410e6a3ae3b63207b7c542860907 and fixed in 5.15.212 with commit c7bef84740d1d57848c74f6f5b996606e43ea4fe Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 6.1.178 with commit d0a469122e7bf8338fec1949fb1e8e1290ed8caa Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 6.6.145 with commit 7470511d085af1c7a043a60e53d52b512d5a10b1 Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 6.12.97 with commit 16a1ecf39c217e3d164bd32ef2a4f650abc067fa Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 6.18.40 with commit 77bb0bbfcc4e777ca653174689e5e363f8ee63d1 Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 7.1.5 with commit 1c89da3baa2b1f269178afa87dc30479b8535776 Issue introduced in 6.0 with commit aa7253c2393f6dcd6a1468b0792f6da76edad917 and fixed in 7.2-rc1 with commit 0c054227479ed7e36ebccb3a558bc0ef698264f6 Issue introduced in 5.18.18 with commit 8a8315a5960bd2b5ffc75f44fc089e57c3b17c44 Issue introduced in 5.19.2 with commit ff20f1875889dbe4a67c9298e609d7c88cf6456d 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-2026-72422 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/server/smb2pdu.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/c7bef84740d1d57848c74f6f5b996606e43ea4fe https://git.kernel.org/stable/c/d0a469122e7bf8338fec1949fb1e8e1290ed8caa https://git.kernel.org/stable/c/7470511d085af1c7a043a60e53d52b512d5a10b1 https://git.kernel.org/stable/c/16a1ecf39c217e3d164bd32ef2a4f650abc067fa https://git.kernel.org/stable/c/77bb0bbfcc4e777ca653174689e5e363f8ee63d1 https://git.kernel.org/stable/c/1c89da3baa2b1f269178afa87dc30479b8535776 https://git.kernel.org/stable/c/0c054227479ed7e36ebccb3a558bc0ef698264f6