From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 001722D5A19; Mon, 13 Apr 2026 16:39:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098383; cv=none; b=t+ENOhbngxdkLwICd6Yn7HTV48UrGmpRbQJqN6+H7ILwN1GAXgTqBoPEqcvolfEnMoiV1FwM6oThEsl7RhMi4zeHAwvlPCI1gXrhrED5E1WostmwE/0wK/eG9J9bTJzEEiBWYzio0L71tXN1cVE80aos+SVlK//FOtxZTAW9MFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098383; c=relaxed/simple; bh=BRZE2zp4Vzr5lYgebO75alVIxPZXJzy+gXE420L/UVU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UnfBQNOO6HYhiGQZ4XOHW1jpIMwVYNQczY9gxbvT1h0ryTfQZiI7z86RXj7duJm/OKVZi58YCrWHon7Ts+YlBWx1gtx4W01AmzXiDXdPBnI7Y2QwTBeRs2vP2OigevwXVhsmANEI7x4LtOAgkVniN4gQXjQLsOWxhnVpz+e6Z4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C55in2RM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="C55in2RM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8ADDBC2BCAF; Mon, 13 Apr 2026 16:39:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776098382; bh=BRZE2zp4Vzr5lYgebO75alVIxPZXJzy+gXE420L/UVU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C55in2RMiJBXJAZaVC+jXzaW1Nflf5HCTOTTm6qcXuEXz+zGtdjAy6LA5E6gDhAz4 JmmEwu3MuL8adbfT1292T5BtJR/oL+I7ybds9iIXVlZZrYdPUtpwurH+RjwbtL9zRj vOIj56A/yMs44/BKz+OXAm4+FBGmSu4Eey1IU8iU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com, Jens Axboe , Robert Garcia Subject: [PATCH 5.15 502/570] io_uring/tctx: work around xa_store() allocation error issue Date: Mon, 13 Apr 2026 18:00:33 +0200 Message-ID: <20260413155849.258514353@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe commit 7eb75ce7527129d7f1fee6951566af409a37a1c4 upstream. syzbot triggered the following WARN_ON: WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51 which is the WARN_ON_ONCE(!xa_empty(&tctx->xa)); sanity check in __io_uring_free() when a io_uring_task is going through its final put. The syzbot test case includes injecting memory allocation failures, and it very much looks like xa_store() can fail one of its memory allocations and end up with ->head being non-NULL even though no entries exist in the xarray. Until this issue gets sorted out, work around it by attempting to iterate entries in our xarray, and WARN_ON_ONCE() if one is found. Reported-by: syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com Link: https://lore.kernel.org/io-uring/673c1643.050a0220.87769.0066.GAE@google.com/ Signed-off-by: Jens Axboe [ Modify the function in io_uring.c because it's located here in v5.15. ] Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -8699,8 +8699,19 @@ static int io_uring_alloc_task_context(s void __io_uring_free(struct task_struct *tsk) { struct io_uring_task *tctx = tsk->io_uring; + struct io_tctx_node *node; + unsigned long index; - WARN_ON_ONCE(!xa_empty(&tctx->xa)); + /* + * Fault injection forcing allocation errors in the xa_store() path + * can lead to xa_empty() returning false, even though no actual + * node is stored in the xarray. Until that gets sorted out, attempt + * an iteration here and warn if any entries are found. + */ + xa_for_each(&tctx->xa, index, node) { + WARN_ON_ONCE(1); + break; + } WARN_ON_ONCE(tctx->io_wq); WARN_ON_ONCE(tctx->cached_refs);