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 8E7373783D1 for ; Tue, 21 Jul 2026 14:29:11 +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=1784644152; cv=none; b=EaoBvQSAMf3CqTN/OBxiFxLrGA9IuLeePzrN2HxkE2p71uRgd2GuqFLZ005orQbkMPrbNc5OrJyE/WpyRJeaLY6TRqQFZDbpaCGAEKQviztFGbGYVdpsE5qZ2Lst7DsSeo8FzHXP5bvg+l+yseBlQrwc55CJBnin0mSyzI5NSps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784644152; c=relaxed/simple; bh=MTxambI95VvodLImfc3jvwYatAcoAiRVv7LH9gqxj1E=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=sse6JuWT6x0iNzqnJ46kKKGAwALZBHLGePRwQsYijBnBLj3evHgaMZxTTmbA7VxFdVXZvME+oStu5oTPkCzUHtxpR2IQa8WxrxbU1mKAdaa973eC/OijZUEvkUHhi9HQgjUztqHO1q76gacOZLDMUDHAAAj94Rz6fYlxVNZx35E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XnKINOW/; 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="XnKINOW/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D88B01F000E9; Tue, 21 Jul 2026 14:29:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784644151; bh=4iKSMtzpRWwnEKYOIHgQ2jrdDFHN0YEVsZvSPc4H0Cw=; h=Subject:To:Cc:From:Date; b=XnKINOW/224hVtcOzoNyFQPo3Uc45os9EwtLDp1fREVEOt/+50PTPI64bILJMaoUj wjahz3Q5oyqxgEvmJ4iFQMsPeM7P26Xlw5FD0QfsSFqA3BcUzc+nb6HOMBtifKK2A3 OQULk3v20Z+bYniAHE0iQ6TMaofLVLR/3Rqm7Ex4= Subject: FAILED: patch "[PATCH] ksmbd: fix durable reconnect double-bind race in" failed to apply to 5.15-stable tree To: dddhkts1@gmail.com,linkinjeon@kernel.org,stfrench@microsoft.com Cc: From: Date: Tue, 21 Jul 2026 16:28:53 +0200 Message-ID: <2026072153-oxidation-gong-003f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 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 7ce4fc40018de07f05f3035241122d992610dbfb # git commit -s git send-email --to '' --in-reply-to '2026072153-oxidation-gong-003f@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 7ce4fc40018de07f05f3035241122d992610dbfb Mon Sep 17 00:00:00 2001 From: Gil Portnoy Date: Thu, 28 May 2026 00:00:00 +0000 Subject: [PATCH] ksmbd: fix durable reconnect double-bind race in ksmbd_reopen_durable_fd Two concurrent same-user DHnC reconnects can both observe fp->conn == NULL before either sets it. ksmbd_reopen_durable_fd() checks fp->conn to guard against a handle already being reconnected, but the check and the binding assignment are not atomic: both threads pass the guard, both call ksmbd_conn_get() on the same fp, and both eventually reach kfree(fp->owner.name) -- a double-free of the owner.name slab object. The double-bound ksmbd_file also causes a write-UAF on the 344-byte ksmbd_file_cache object when a concurrent smb2_close() spins on fp->f_lock after the object has been freed by the losing reconnect path. KASAN on 7.1-rc5 (48-thread concurrent reconnect, 3000 cycles): BUG: KASAN: double-free in ksmbd_reopen_durable_fd+0x268/0x308 BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xac/0x150 Write of size 4 at offset 24 into freed ksmbd_file_cache object Five double-bind windows observed; 63 total KASAN reports triggered. Fix: validate and claim fp->conn under write_lock(&global_ft.lock) so the check-and-claim is atomic. ksmbd_lookup_durable_fd() already treats fp->conn != NULL as "in use" and skips such an fp; setting fp->conn before dropping the lock closes the race. ksmbd_conn_get() is a non-sleeping refcount increment, safe under the rwlock. The rollback path on __open_id() failure also clears fp->conn/tcon under the lock so concurrent readers see a consistent state. Fixes: b1f1e80620de ("ksmbd: centralize ksmbd_conn final release to plug transport leak") Assisted-by: Henry (Claude):claude-opus-4 Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 4d2d33df6231..ba3355a6057a 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -1390,19 +1390,19 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, struct ksmbd_file *fp) struct ksmbd_lock *smb_lock; unsigned int old_f_state; + write_lock(&global_ft.lock); if (!fp->is_durable || fp->conn || fp->tcon) { + write_unlock(&global_ft.lock); pr_err("Invalid durable fd [%p:%p]\n", fp->conn, fp->tcon); return -EBADF; } if (has_file_id(fp->volatile_id)) { + write_unlock(&global_ft.lock); pr_err("Still in use durable fd: %llu\n", fp->volatile_id); return -EBADF; } - old_f_state = fp->f_state; - fp->f_state = FP_NEW; - /* * Initialize fp's connection binding before publishing fp into the * session's file table. If __open_id() is ordered first, a @@ -1413,11 +1413,17 @@ int ksmbd_reopen_durable_fd(struct ksmbd_work *work, struct ksmbd_file *fp) */ fp->conn = ksmbd_conn_get(conn); fp->tcon = work->tcon; + write_unlock(&global_ft.lock); + + old_f_state = fp->f_state; + fp->f_state = FP_NEW; __open_id(&work->sess->file_table, fp, OPEN_ID_TYPE_VOLATILE_ID); if (!has_file_id(fp->volatile_id)) { + write_lock(&global_ft.lock); fp->conn = NULL; fp->tcon = NULL; + write_unlock(&global_ft.lock); ksmbd_conn_put(conn); fp->f_state = old_f_state; return -EBADF;