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 136ED58E2BF for ; Fri, 11 Sep 2026 20:05:33 +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=1789157136; cv=none; b=J7Oa6XH39ZrTD+oDMOUI18gU1LfpD61EdGryZJsnZD6QMjfDr76yByHG9gSHLNyoFpZYlpF+aWQOWpnzWXbs5SltrpqbGkHTk5Cd980yEa+4FUlUxot5m6g82NjuUvzXodOrHf6kjZwafDGe8DUXnyt5xNrMpweyTBOHalqfThM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157136; c=relaxed/simple; bh=1xV0dd3vv+oxcrRS/o02K7KU6W/EqlLVMkcmO1Ml4BM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=gnzAOMxh56RpIpVbCL0hDpLNXjnoZYdWHpO47uij2h/K0imtVD2dI6/IvwQRERTQsVrXGJKsGAYKHEKzi+gcZF8i2OpXONDIEQa8WPsl4kh/vvNuApqZtQd6ptgxiwvEW+Bvv3LzDdmV1P7iTaDwT/stFoDmE/PqxGfhpwDyxJ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vsZowZj3; 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="vsZowZj3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7550D1F000FF; Fri, 11 Sep 2026 20:05:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157130; bh=xc0oVsOFr0CF15jA+g4GgZb41T5o1iuWpYPLncFZ1qg=; h=From:To:Cc:Subject:Date:Reply-To; b=vsZowZj394AsCwfKyyiHSUij0biVv/a+3xCOAwguOZPoOivrHjLofkIpY3sgvxgTs /STCZb0qCIW1Rh9D5KCZ9x6Vplvu1wweycTJWa/Vw8h1g7qGfMA5Kkd0BXFORObY25 9P4VSEkBw3fYjkYRJl2p4ieg/ENdytkHte9XCoxA= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89747: tracing: Fix use-after-free in trace_pipe read on sub-buffer order change Date: Fri, 11 Sep 2026 21:47:16 +0200 Message-ID: <2026091106-CVE-2026-89747-b5d5@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=3403; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=0gRaglg+2PHw8eKiYaO5Qssae2QNkVwRTmocK7ot5gY=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIvtcJ+zlW/jV6tO84+nqf1etSru447Z98TTRlKY5V +3+lc9J7ohlYRBkYpAVU2T5so3n6P6KQ4pehranYeawMoEMYeDiFICJLDvMsOBQ/Npw0w5mSzOR 9TEVRan3956dtoJhwaQJ21Svn9z/2b93uoyYwZXHq3ibKwA= 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: tracing: Fix use-after-free in trace_pipe read on sub-buffer order change Writing to buffer_subbuf_size_kb calls ring_buffer_subbuf_order_set(), which frees every sub-buffer of the ring buffer, including the reader page, and replaces them with newly allocated ones. Readers of trace_pipe hold pointers into those pages. ring_buffer_peek() looks up an event under cpu_buffer->reader_lock but returns the event pointer after dropping the lock, and peek_next_entry() then calls ring_buffer_event_length() and ring_buffer_event_data() on it. If the sub-buffer order is changed in that window, the reader dereferences freed memory: BUG: KASAN: use-after-free in ring_buffer_peek+0x3e0/0x430 Read of size 1 at addr ffff88802a4cf010 by task syz-executor989/6002 Freed by: free_buffer_page kernel/trace/ring_buffer.c:398 [inline] ring_buffer_subbuf_order_set+0x1325/0x18e0 kernel/trace/ring_buffer.c:7444 buffer_subbuf_size_write+0x182/0x280 kernel/trace/trace.c:8221 Take trace_access_lock(RING_BUFFER_ALL_CPUS) around the order change. This is the lock trace_pipe readers already hold across their entire peek-and-print loop, so the swap can no longer race with a reader that is dereferencing a peeked event. The Linux kernel CVE team has assigned CVE-2026-89747 to this issue. Affected and fixed versions =========================== Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 6.12.109 with commit 05ebe1e1d7d38c2612bacfefe043a33572ae34cb Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 6.18.50 with commit ddbe921ed16a0ad2d9e09574c3f3aabec7528325 Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.2.4 with commit 7a49d19ff9baaf61217e5ec14199c18bc2d93ee4 Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.3-rc1 with commit 372f8534244d632ad5118e8a87a11291b01712d3 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-2026-89747 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: kernel/trace/trace.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/05ebe1e1d7d38c2612bacfefe043a33572ae34cb https://git.kernel.org/stable/c/ddbe921ed16a0ad2d9e09574c3f3aabec7528325 https://git.kernel.org/stable/c/7a49d19ff9baaf61217e5ec14199c18bc2d93ee4 https://git.kernel.org/stable/c/372f8534244d632ad5118e8a87a11291b01712d3