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 1B964583AA6 for ; Fri, 11 Sep 2026 19:55:32 +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=1789156538; cv=none; b=cEhksR1oC1q1bfUFpMT4YsfzIGmXquVGZXNNgVZ6HkhfzdSnKO4lEgjlmhtJdmYrCYNz5DTWdE2Op/j2TTlgIoijH+d9piWDy1t3QC1sI/pls2fJaVvURg/bPUETc2hkBoA/RjegSDntKJqimv1Beqv5t6Rt34UROhikJ5mLpEA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156538; c=relaxed/simple; bh=VaQ3ZJ8dMXXrTa1gbl4OeqCNPFY2uMGk/Smah4t3hyA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=XlZrRGUv5WTcYAgXhqFZDxRK3yWxXAnmL5IaJxTre7EJo+sJ4ALQjpNnhFr1vG1neHaC5s9Ne2Bw5l3MzgNTzGzo/3Tk5sLmHD2iYWWxSF2qKZniibNar9tCreUaCOyxMLoNsaAirVOkkFLOXcmdnjXd89YFgBM3FfsLuG/bzQc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gWwjvec9; 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="gWwjvec9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CBDD91F00893; Fri, 11 Sep 2026 19:55:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156529; bh=zgHYTlFc7r0gckJVm/+qEZTiKbRFbKCME51LDgBE084=; h=From:To:Cc:Subject:Date:Reply-To; b=gWwjvec9vGxb+0xiym03olYyOxz94+AgONZCRvT/kTt3Z6vSdQckwRexyzyXgtvH8 BHGDIQelzaGUZwyH4PSh86b2p14llkSji+zcaxMSlANg83busFnqlqnFAFYdpyB6pf YpXgG/+/cwWQxac5TCdYdyqKqXNjqT1vPPvuI/CY= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89546: SUNRPC: close backchannel before destroying callback service Date: Fri, 11 Sep 2026 21:43:55 +0200 Message-ID: <2026091120-CVE-2026-89546-57fc@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=3064; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=RxVkMRC1qaVw8+Tu+r+2M8qNyOhFRf6rzb1QxePu6dg=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIhPEX9UG71VwYVqQ/3n/kUX3rTwjJnCGT57yqsvs5 W6X0J6pHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjAR4dMMC1bfmeRUt3nWufvq uy5quKltu7XpyXeGBRtdQ725ZoTE9vZ9fN4sfr768UkzCwA= 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: SUNRPC: close backchannel before destroying callback service A backchannel receive can complete a request while the NFS callback service is being torn down. xprt_complete_bc_request() removes the request from bc_pa_list, drops bc_alloc_count, marks the request in use, and then asks xprt_enqueue_bc_request() to hand it to the callback service. If teardown has already cleared xprt->bc_serv, xprt_enqueue_bc_request() currently returns without enqueueing or freeing the committed request. The xprt_get() taken on entry is leaked as well. If the producer wins the race before bc_serv is cleared, it can also enqueue onto sv_cb_list after nfs_callback_down() has stopped the callback threads, leaving the request linked to a svc_serv that is about to be freed. Close the producer side before callback threads are stopped. Add xprt_svc_shutdown_bc() to clear xprt->bc_serv under bc_pa_lock, and call it on callback shutdown and callback-start failure before stopping the service threads. Requests that lose the NULL transition in xprt_enqueue_bc_request() are released through the normal backchannel free path after balancing bc_slot_count. Finally, drain any remaining sv_cb_list requests after the callback threads have stopped and before svc_destroy() frees the service. The Linux kernel CVE team has assigned CVE-2026-89546 to this issue. Affected and fixed versions =========================== Issue introduced in 6.19 with commit 441244d4273a8037b265fd254dfdaca5fa736ee2 and fixed in 7.2.4 with commit 6debde9e3e6ae21dcca75837b4247b13ca4ea2b8 Issue introduced in 6.19 with commit 441244d4273a8037b265fd254dfdaca5fa736ee2 and fixed in 7.3-rc1 with commit 3674f780f47d2906b5a0f7199b66973067bdfeca 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-2026-89546 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/nfs/callback.c include/linux/sunrpc/bc_xprt.h net/sunrpc/backchannel_rqst.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/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8 https://git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca