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 4597E4E021E for ; Thu, 17 Sep 2026 16:18:17 +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=1789661898; cv=none; b=Uheffjg5nhSi1YB5VSuO2J6HtWEd0kv9LNOMwzODEPPOewaTh6+Alve5fnfZzXzvZ9C0oEUo4IsrhEP9Bm6uMp+zOgIqFuMzw+UMq8pMwn6h4JKCc5n802zfn1HNe5oUnch2ZFIvs6wKTD8kDgU8rqDNt1VEI0rbyI6YlVXZMf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789661898; c=relaxed/simple; bh=8msF5q7ZR2hIPMdT3Q8fXOgmBHV6Htqb69zZqyfg5AI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=PbsWIF8WJTyrgGPMTjCIll8NctB/IH4M4PAcUqBQh7EVtS04sNBYXy4n9ZkoS8NtCMKK1OfYIRro1ubnb64ZXPq9UucL/Qjy23VV6i9WsdU9qAXHHGJ+GfjnAJs21t17qGqajE8TlpyR2MYlW4I079B57Ti/sY92UZJhNeVuG70= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2OgS+hf5; 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="2OgS+hf5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9578E1F00893; Thu, 17 Sep 2026 16:18:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789661897; bh=BB6OmDaWJbxdz/9vk6M6eRQnVoPXrRwfauKE6/zom08=; h=From:To:Cc:Subject:Date:Reply-To; b=2OgS+hf5YWIL0yZtl38ec58CC9pZ5rKkuklQSSxjAYDHM/fO24e/MwW3RMhuXoIGZ i8CSbiOWPjEm9eCGnGij7SRyfo0+9tML4P83bdwB7zSLXuLwhDC9eKqFDD5PmQv02L 5XSUyNVFsEtKgIzZ2m8tU/T/COx/VvCBVShuodK4= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-90174: ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user() Date: Thu, 17 Sep 2026 17:10:04 +0100 Message-ID: <2026091728-CVE-2026-90174-eddb@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=7822; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=oLV5B5HP1fH13Yp7XQxNqhnpkeLBNz8FHj6SXa82ZJY=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBGoOsd35LXr3+OOzqYeNyiZu3n/2678w2yDFi+bf0 g/fNSxq64hlYRBkYpAVU2T5so3n6P6KQ4pehranYeawMoEMYeDiFICJrApkmMOjNcO2oT14EZvx 7mIzYc8LGXs6SxkW7JEL15hyf4YUs67gvidlnLW5U7dGAAA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user() ksmbd_alloc_user() copies resp->hash_sz bytes out of the mountd IPC login response with user->passkey_sz = resp->hash_sz; user->passkey = kmalloc(resp->hash_sz, KSMBD_DEFAULT_GFP); if (user->passkey) memcpy(user->passkey, resp->hash, resp->hash_sz); resp->hash_sz is a __u16 supplied by the response, but resp->hash[] is only KSMBD_REQ_MAX_HASH_SZ bytes. A malformed or malicious login response can set hash_sz well beyond that (up to 65535), so the memcpy() reads past the end of the response object. ipc_validate_msg() does not bound hash_sz, so reject any response whose hash_sz exceeds the on-stack hash[] buffer before allocating and copying. [ 2030.238706] BUG: KASAN: slab-out-of-bounds in ksmbd_alloc_user+0x278/0x680 [ 2030.240549] Read of size 65535 at addr ffff888121bb6680 by task kworker/4:1/18611 [ 2030.242296] [ 2030.242710] CPU: 4 UID: 0 PID: 18611 Comm: kworker/4:1 Not tainted 7.1.0-next-20260623-virtme #96 PREEMPT(lazy) [ 2030.242732] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 2030.242743] Workqueue: ksmbd-io handle_ksmbd_work [ 2030.242763] Call Trace: [ 2030.242769] [ 2030.242776] dump_stack_lvl+0xa2/0xd0 [ 2030.242794] print_address_description+0x77/0x200 [ 2030.242815] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242831] print_report+0x58/0x70 [ 2030.242848] kasan_report+0x117/0x150 [ 2030.242869] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242888] kasan_check_range+0x3c7/0x3f0 [ 2030.242908] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242925] __asan_memcpy+0x29/0x70 [ 2030.242942] ksmbd_alloc_user+0x278/0x680 [ 2030.242960] ksmbd_login_user+0xc3/0x120 [ 2030.242978] ntlm_authenticate+0x5e6/0x1b00 [ 2030.243017] ? __pfx_ntlm_authenticate+0x10/0x10 [ 2030.243035] ? ksmbd_session_lookup+0x188/0x1d0 [ 2030.243054] ? __pfx_ksmbd_session_lookup+0x10/0x10 [ 2030.243090] ? __sanitizer_cov_trace_switch+0x7b/0x140 [ 2030.243108] smb2_sess_setup+0x1e4a/0x27b0 [ 2030.243126] ? copy_from_kernel_nofault+0x199/0x300 [ 2030.243156] ? __pfx_smb2_sess_setup+0x10/0x10 [ 2030.243173] ? get_smb2_cmd_val+0xe3/0x1c0 [ 2030.243208] handle_ksmbd_work+0x954/0x1280 [ 2030.243230] ? __pfx_handle_ksmbd_work+0x10/0x10 [ 2030.243249] ? process_scheduled_works+0xa07/0x1490 [ 2030.243270] ? process_scheduled_works+0xa07/0x1490 [ 2030.243291] process_scheduled_works+0xa70/0x1490 [ 2030.243320] ? __pfx_process_scheduled_works+0x10/0x10 [ 2030.243340] ? do_raw_spin_lock+0x130/0x300 [ 2030.243358] ? lock_is_held_type+0x7b/0x110 [ 2030.243388] worker_thread+0x932/0xe20 [ 2030.243415] kthread+0x38a/0x470 [ 2030.243431] ? __pfx_worker_thread+0x10/0x10 [ 2030.243451] ? __pfx_kthread+0x10/0x10 [ 2030.243467] ret_from_fork+0x484/0x910 [ 2030.243485] ? __pfx_ret_from_fork+0x10/0x10 [ 2030.243501] ? __switch_to+0xc77/0x12c0 [ 2030.243523] ? __pfx_kthread+0x10/0x10 [ 2030.243540] ret_from_fork_asm+0x1a/0x30 [ 2030.243564] [ 2030.243570] [ 2030.290164] Allocated by task 19279: [ 2030.290911] kasan_save_track+0x3e/0x80 [ 2030.292179] __kasan_kmalloc+0x72/0x90 [ 2030.293217] __kvmalloc_node_noprof+0x3ff/0x6b0 [ 2030.294467] handle_generic_event+0x59b/0x750 [ 2030.295345] genl_family_rcv_msg_doit+0x238/0x340 [ 2030.296553] genl_rcv_msg+0x606/0x7b0 [ 2030.297129] netlink_rcv_skb+0x22b/0x4a0 [ 2030.298500] genl_rcv+0x2d/0x40 [ 2030.299273] netlink_unicast+0x7ba/0x930 [ 2030.300019] netlink_sendmsg+0x8c3/0xb00 [ 2030.301073] __sock_sendmsg+0xec/0x140 [ 2030.301579] __sys_sendto+0x357/0x470 [ 2030.302255] __x64_sys_sendto+0xe3/0x100 [ 2030.303425] do_syscall_64+0x135/0x460 [ 2030.304763] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 2030.305594] [ 2030.305819] The buggy address belongs to the object at ffff888121bb6640 [ 2030.305819] which belongs to the cache kmalloc-192 of size 192 [ 2030.309595] The buggy address is located 64 bytes inside of [ 2030.309595] allocated 166-byte region [ffff888121bb6640, ffff888121bb66e6) [ 2030.312484] [ 2030.312719] The buggy address belongs to the physical page: [ 2030.314315] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121bb6 [ 2030.316481] head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 [ 2030.318248] flags: 0x100000000000040(head|node=0|zone=2) [ 2030.319662] page_type: f5(slab) [ 2030.320242] raw: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468 [ 2030.321911] raw: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000 [ 2030.324413] head: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468 [ 2030.326150] head: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000 [ 2030.327960] head: 0100000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff [ 2030.329615] head: ffff888121bb7ab0 0000000000000000 00000000ffffffff 0000000000000000 [ 2030.331861] page dumped because: kasan: bad access detected [ 2030.332946] [ 2030.333502] Memory state around the buggy address: [ 2030.334698] ffff888121bb6580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 2030.336475] ffff888121bb6600: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 [ 2030.338143] >ffff888121bb6680: 00 00 00 00 00 00 00 00 00 00 00 00 06 fc fc fc [ 2030.339116] ^ [ 2030.341315] ffff888121bb6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 2030.342801] ffff888121bb6780: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb [ 2030.344643] ================================================================== Found with ksmbdzzer [2], a KSMBD fuzzer that drives libFuzzer with a kcov-dataflow [1] coverage vector: it folds each instrumented comparison/argument's runtime operand value together with its PC (the default arm mixes them as pc⊕val) so that a new operand value at a known site counts as new coverage. [1] https://lwn.net/Articles/1077606/ [2] https://github.com/yskzalloc/kcov-dataflow The Linux kernel CVE team has assigned CVE-2026-90174 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.2.6 with commit 497c221bf6b2f659511719a6acfae84cc1be1caf Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.3-rc1 with commit 7405d0ba294306721843bc551611775e6edef516 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-2026-90174 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/mgmt/user_config.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/497c221bf6b2f659511719a6acfae84cc1be1caf https://git.kernel.org/stable/c/7405d0ba294306721843bc551611775e6edef516