From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794273615; b=fq7tv0i0fHN5TCDrQ++PoAOOxoUnmhnm84H4xEdpEWGbGBrEEcNzZW9vKj8aIqARyvNc a859PaHrYuW3+U+CRjeP15MSQiAehOVzo24d3Zdrsj9Ceqfld17kECmwOkQctAa8C+l+l ntGgamGBDjLP7+AXi06C+O40sEoq1RLILiEmwzq9cl91+o1xFZFuvo49hR1JANURkOp3h 83w2dwqQpAfQHYl7qbH6r7M/1QEJOOJpsBdtGf4tNsB6ADz/6Gq/wjpZv2gX5dhJojIu0 txGSw//vKndqomAQxLRZhHrJrsyC49Ab2nAIkYFJ2TfLktO377ZnwC4ReN50Byqo6WQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273615; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=eW+HBXIsxjQsqJkePBjUESHyBcP95UbK4VKIUGP5Ekk=; b=i8f/o0XRUJPxN0IuHcu7BuRy4DPruTqfS+bKNEWN0qsevNYsPMc8osSL1XULLs/ldHNA P0LIjvzyKuLGErd7IP1hblOvbrWhEHVypWHBwJ0VkHwuR/FybiWt/3convnSPu6I0s7sb ObUvihm5VzrawPp/1QmAGh70pl3ucLqFyglIrIItJ4nQtbkLuX8iaSRjGrechudxe0dAd NMy+OR7wQ1NWTzlyI1Q7C7GmyukF0itJXrRBNKm5wQqBXr2zH/xqjOFT6He313Pmyh8JC 8PuUJ9bWfyUk23e6EmxHj7OBelR2IV23voj7O0G+v2y9clgVg5mB/xYCocyVCkhBmJA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="A/KGobE5"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DD5B606A321 for ; Tue, 10 Nov 2026 01:20:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=A/KGobE5 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99F421F008A7; Tue, 10 Nov 2026 01:20:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273615; bh=eW+HBXIsxjQsqJkePBjUESHyBcP95UbK4VKIUGP5Ekk=; h=From:To:Cc:Subject:Date; b=A/KGobE5QVqrmmTEAMUBEuqhOFMf52ZlAkHcK4geyM2o3D5khdEwj7KGJFAJl5X6v mwqcUA1EAY2mJnEtaZQccsOOX1KqF3EUkFom9OXWIHhx2Qn6xo0BLJ5KDPW03I4Q5R tTADFfCbxqFve+c4e03P5ss4SLddc04AqdmUFRMNGgM64KW3Joc4IHWyfX+tNyQLOJ 5QtXbCciRvEvo/Q8jvfSCqtrsfy0Nl0U2Ekt3mKWN/GKEFBby5S2K6NYUcwGH1+N6L 4LjJ26VdA5GyI6gSRhmQfeWDmqVca9ilMJerpGRjwYcB4SVH7/kQu49siMwI9RRjS5 FPAP7rqI6I3/w== From: Sasha Levin To: yuz08559@gmail.com, mkp@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] scsi: target: Fix demo-mode dynamic ACL dev-entry UAF vs LUN teardown" failed to apply to 5.15-stable tree Date: Mon, 9 Nov 2026 20:20:13 -0500 Message-ID: <20261109202013-failed-5.15-6a6e7d7230cd@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6a6e7d7230cd4e0a6c003bae5b85bf37a1e77b94 # git commit -s git send-email --to '' --in-reply-to '20261109202013-failed-5.15-6a6e7d7230cd@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 6a6e7d7230cd4e0a6c003bae5b85bf37a1e77b94 Mon Sep 17 00:00:00 2001 From: Yu Zhang Date: Wed, 14 Oct 2026 11:37:46 +1000 Subject: [PATCH] scsi: target: Fix demo-mode dynamic ACL dev-entry UAF vs LUN teardown A demo-mode (generate_node_acls=1) login that allocates a dynamic NodeACL populates that ACL's per-LUN dev entries in core_tpg_add_node_to_devs() *before* the ACL is linked onto tpg->acl_node_list by target_add_node_acl(): core_tpg_check_initiator_node_acl(): ... core_tpg_add_node_to_devs(acl, tpg, NULL); /* builds deves */ target_add_node_acl(acl); /* only now listed */ The LUN teardown sweep, core_clear_lun_from_tpg(), enumerates only tpg->acl_node_list, so a dev entry whose ACL is still in the window above is invisible to the sweep and is never disabled. It is left on the se_lun->lun_deve_list after core_tpg_remove_lun() frees the se_lun; when the same unpacked_lun is later re-added and the se_lun is reallocated at the same address, the stale dev entry is rediscovered by target_nacl_find_deve() and core_enable_device_list_for_node() corrupts lun_deve_list: BUG: KASAN: slab-use-after-free ... core_enable_device_list_for_node+0x5ce/0x880 core_tpg_add_node_to_devs+0x169/0x190 core_dev_add_lun+0x146/0x190 target_fabric_port_link+0xe9/0x1b0 configfs_symlink+0x381/0xae0 __x64_sys_symlink+0x55/0x80 The demo-mode login path that drives the ACL/dev-entry creation is reachable by an unauthenticated initiator; the colliding LUN add/remove is a local configfs operation. Commit 49cb77e297dc ("target: Avoid mappedlun symlink creation during lun shutdown") introduced se_lun->lun_shutdown and guarded the *explicit* ACL MappedLUN path (target_fabric_mappedlun_link()), but the demo-mode automatic path, core_tpg_add_node_to_devs() -> core_enable_device_list_for_node(), was never given the equivalent guard, and the publish-after-populate ordering in core_tpg_check_initiator_node_acl() was left unchanged. Fix it in three cooperating parts: 1) Publish the dynamic NodeACL onto acl_node_list *before* creating its dev entries, so the teardown sweep can observe them. 2) Refuse to attach a dev entry to an se_lun that is shutting down, checked under nacl->lun_entry_mutex -- the same lock the sweep takes -- so once the sweep has passed an ACL any later enable for that LUN observes lun_shutdown and skips it. 3) In core_enable_device_list_for_node(), insert the new dev entry onto lun->lun_deve_list while still holding nacl->lun_entry_mutex, in both the replace and the new-entry branch. Previously the entry was added to nacl->lun_entry_hlist under the mutex but to lun->lun_deve_list only after dropping it; with the ACL now published early, the sweep could take the mutex in that gap, find the entry on the hlist, core_disable_device_list_for_node() it (list_del() on the not-yet- linked lun_link succeeds and the entry is freed), and then the enable would list_add_tail() the freed entry back onto lun_deve_list. Linking both lists under the mutex makes enable and the sweep mutually exclusive, closing that window. core_tpg_add_node_to_devs() already ignores the return value of core_enable_device_list_for_node(), so a shutting-down LUN is simply skipped. Cc: stable@vger.kernel.org Fixes: 49cb77e297dc ("target: Avoid mappedlun symlink creation during lun shutdown") Signed-off-by: Yu Zhang Tested-by: Yu Zhang Link: https://patch.msgid.link/20261014013746.46705-1-yuz08559@gmail.com Signed-off-by: Martin K. Petersen (Oracle) --- drivers/target/target_core_device.c | 18 +++++++++++++++--- drivers/target/target_core_tpg.c | 10 +++++++++- 2 files changed, 24 insertions(+), 4 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 9db2201aa553f..c5d5d6a91fee7 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -349,6 +349,19 @@ int core_enable_device_list_for_node( new->attach_count++; mutex_lock(&nacl->lun_entry_mutex); + /* + * Do not attach a new dev entry to an se_lun that is being torn down. + * lun_shutdown is set by core_tpg_remove_lun() before its + * core_clear_lun_from_tpg() sweep; checking it here under the same + * nacl->lun_entry_mutex the sweep takes guarantees that once the sweep + * has passed this ACL no dev entry can be left dangling on the + * se_lun->lun_deve_list that is about to be freed. + */ + if (lun->lun_shutdown) { + mutex_unlock(&nacl->lun_entry_mutex); + ret = -ENODEV; + goto free_stats; + } orig = target_nacl_find_deve(nacl, mapped_lun); if (orig && orig->se_lun) { struct se_lun *orig_lun = orig->se_lun; @@ -375,12 +388,12 @@ int core_enable_device_list_for_node( new->se_lun_acl = lun_acl; hlist_del_rcu(&orig->link); hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist); - mutex_unlock(&nacl->lun_entry_mutex); spin_lock(&lun->lun_deve_lock); list_del(&orig->lun_link); list_add_tail(&new->lun_link, &lun->lun_deve_list); spin_unlock(&lun->lun_deve_lock); + mutex_unlock(&nacl->lun_entry_mutex); kref_put(&orig->pr_kref, target_pr_kref_release); wait_for_completion(&orig->pr_comp); @@ -393,11 +406,10 @@ int core_enable_device_list_for_node( new->se_lun = lun; new->se_lun_acl = lun_acl; hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist); - mutex_unlock(&nacl->lun_entry_mutex); - spin_lock(&lun->lun_deve_lock); list_add_tail(&new->lun_link, &lun->lun_deve_list); spin_unlock(&lun->lun_deve_lock); + mutex_unlock(&nacl->lun_entry_mutex); target_luns_data_has_changed(nacl, new, true); return 0; diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index ccff9f6e48266..e615e5e304273 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -266,6 +266,15 @@ struct se_node_acl *core_tpg_check_initiator_node_acl( kref_get(&acl->acl_kref); acl->dynamic_node_acl = 1; + /* + * Publish the dynamic NodeACL on tpg->acl_node_list before creating + * its demo-mode MappedLUN dev entries below, so that a concurrent LUN + * teardown sweep (core_clear_lun_from_tpg(), which walks acl_node_list) + * can observe and disable those dev entries. Otherwise a dev entry can + * be left on an se_lun->lun_deve_list that is about to be freed. + */ + target_add_node_acl(acl); + /* * Here we only create demo-mode MappedLUNs from the active * TPG LUNs if the fabric is not explicitly asking for @@ -275,7 +284,6 @@ struct se_node_acl *core_tpg_check_initiator_node_acl( (tpg->se_tpg_tfo->tpg_check_demo_mode_login_only(tpg) != 1)) core_tpg_add_node_to_devs(acl, tpg, NULL); - target_add_node_acl(acl); return acl; } EXPORT_SYMBOL(core_tpg_check_initiator_node_acl); -- 2.53.0