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 913753DCD83 for ; Mon, 20 Jul 2026 18:08:44 +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=1784570925; cv=none; b=Uz8K+9pVl2kAsirw+CqP2Lkzw97TlKp1EAmnaonZjWzcV6yJVjH+/DNI5PoWc7w2LD3IGx/jx3KrCstB/pko86wYPttVE3eiXud0ryu0FYTCG2qK6MHwpcAVqhPZWMWwzYWiWlgmccoKXeeS61dAAQv6hrpp4ewAhsLfaOBmTZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784570925; c=relaxed/simple; bh=lwPYy9BFwZcmcm/D7UO/+vNtsBrYb74pDgnNDZVBr6I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=syL4k7M9XPWb7DNJQiijeJU/A4747jxyYf0G4Sj95u0ncv4x61poKz5TNEfGa6X8zNAMgvOSKeBM9RNIMEIv4VzKoTKzHisqQjq0XgqKGi7HyHOWrNAmXjlXQhGBLtaiQyWxhBJvbV+VgG8v+Tgi7xX/d5vY4q02SxIUQAoxxRQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m7gdTZ/V; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="m7gdTZ/V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAFD81F00A3D; Mon, 20 Jul 2026 18:08:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784570924; bh=SsTIIZv5oSQrZ5tMNk7Z3PcJZHiujw7FcblCaAPcXVI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=m7gdTZ/VwGpivSrX6e43laVdLwVH6Mcv3462QMRMa0cG/4QugM5iGKR85hPjk5Mg1 vs9KmuZQ3IaV8bCiyfRFX23+7NxFOZ646TY1eM7xaqHScxEPdKfl2qHATv8JFcFDr4 a327cAVVl4ajY3KLm9+SO8fkowiFadSxXc8oHgquZbFvC4lKzwtyyEYm+UY5T/DWYN nD2AOl091ntJIR3BcppVn8R/eOtQA7K4XC7ajpJ74hC/JDTc2bkbOO/RiYvM8owF0G T57i2tRAOKL1LEYO7rS2U+ikDdB/TMJ35R0KcBIzhiGPt3/erVvGQlbRnjbrn5OLwN fga9QDPr8A41w== From: Sasha Levin To: stable@vger.kernel.org Cc: Bryam Vargas , Chaitanya Kulkarni , Christoph Hellwig , Keith Busch , Sasha Levin Subject: [PATCH 6.1.y 3/3] nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page Date: Mon, 20 Jul 2026 14:08:40 -0400 Message-ID: <20260720180840.2922604-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260720180840.2922604-1-sashal@kernel.org> References: <2026071541-clapping-endowment-373b@gregkh> <20260720180840.2922604-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Bryam Vargas [ Upstream commit 53cd102a7a56079b11b897835bd9b94c14e6322c ] nvmet_execute_disc_get_log_page() validates only the dword alignment of the host-supplied Log Page Offset (lpo). The 64-bit offset is then added to a small kzalloc'd buffer that holds the discovery log page and the result is passed straight to nvmet_copy_to_sgl(), which memcpy()s data_len bytes out to the host with no source-side bound check: u64 offset = nvmet_get_log_page_offset(req->cmd); /* 64-bit host */ size_t data_len = nvmet_get_log_page_len(req->cmd); /* 32-bit host */ ... if (offset & 0x3) { ... } /* only check */ ... alloc_len = sizeof(*hdr) + entry_size * discovery_log_entries(req); buffer = kzalloc(alloc_len, GFP_KERNEL); ... status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len); The Discovery controller is unauthenticated -- nvmet_host_allowed() returns true unconditionally for the discovery subsystem -- so the call is reachable pre-authentication by any TCP/RDMA/FC peer that can reach the nvmet target. With a discovery log page of ~1 KiB, an attacker requesting up to 4 KiB starting at offset == alloc_len reads the next slab page out and gets its content returned over the fabric (an empirical run on a default nvmet-tcp loopback target leaked 81 canonical kernel pointers in one Get Log Page response). Pointing the offset at unmapped kernel memory faults the in-kernel memcpy and crashes (or panics, on panic_on_oops=1) the target host instead. The attacker-controlled source-side offset pattern "nvmet_copy_to_sgl(req, 0, buffer + ATTACKER_OFFSET, ...)" is unique to nvmet_execute_disc_get_log_page in the entire nvmet codebase: every other Get Log Page handler in admin-cmd.c either ignores lpo (and silently starts every response at offset 0) or tracks a local destination offset with a fixed source pointer. Validate the host-supplied offset against the log page size, cap the copy length to what is actually available, and zero-fill any remainder of the host transfer buffer. The zero-fill matches the existing short-response pattern in nvmet_execute_get_log_changed_ns() (admin-cmd.c) and prevents leaking transport SGL contents when the host asks for more bytes than the log page contains. Fixes: a07b4970f464 ("nvmet: add a generic NVMe target") Cc: stable@vger.kernel.org Reviewed-by: Chaitanya Kulkarni Reviewed-by: Christoph Hellwig Signed-off-by: Bryam Vargas Signed-off-by: Keith Busch Signed-off-by: Sasha Levin --- drivers/nvme/target/discovery.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c index af3c6793aff032..c143e7a0d36221 100644 --- a/drivers/nvme/target/discovery.c +++ b/drivers/nvme/target/discovery.c @@ -166,6 +166,7 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req) u64 offset = nvmet_get_log_page_offset(req->cmd); size_t data_len = nvmet_get_log_page_len(req->cmd); size_t alloc_len; + size_t copy_len; struct nvmet_subsys_link *p; struct nvmet_port *r; u32 numrec = 0; @@ -239,7 +240,27 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req) up_read(&nvmet_config_sem); - status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len); + /* + * Validate the host-supplied log page offset before copying out. + * Without this check, the host controls a 64-bit byte offset into + * a small kzalloc'd buffer: a value past the log page lets the + * subsequent memcpy read adjacent kernel heap, and a value aimed + * at unmapped kernel memory faults the in-kernel copy and crashes + * the target host. The Discovery controller is unauthenticated, + * so the bug is reachable from any reachable fabric peer. + */ + if (offset > alloc_len) { + req->error_loc = + offsetof(struct nvme_get_log_page_command, lpo); + status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR; + goto out_free_buffer; + } + + copy_len = min_t(size_t, data_len, alloc_len - offset); + status = nvmet_copy_to_sgl(req, 0, buffer + offset, copy_len); + if (!status && copy_len < data_len) + status = nvmet_zero_sgl(req, copy_len, data_len - copy_len); +out_free_buffer: kfree(buffer); out: nvmet_req_complete(req, status); -- 2.53.0