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 845ED3382FA; Mon, 13 Apr 2026 17:00:25 +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=1776099625; cv=none; b=h4XECizhjcW7vG1hPmulj2+xLYH4IRjrpSdFbyuwATEmAeq86tehTwt8VrD2FIh6dSBp5r0Kjr6hni0ydpkqQ23VqheNyWpbgPrBR5qCDxpSvNpAExBbPm46ZQaL4AHCq6jEqC5syJhVDizKenGNVn+sGO7+sXxoa2Pxr4OqHw8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776099625; c=relaxed/simple; bh=1taNT22CiamjziOB4a1Po72QXWOU6A4ZwrLQB0hS3bM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IlMSny/TcAskrMZp9lpx2H0JbQE2Zkh7GlZ4ZzCdChudg8zKRA7mcsg20pPihmdrxgs5N0k9FdvGdtyHyN1AUmdKcN5lusETLygI1Ehf+DmNAHHr1DpiDjpEKy3SusoXy5V23N5lvUi33hYg9bXIwHLhzqaap+KrMcPbUCgS+Hs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=u+AYIeH7; 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="u+AYIeH7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A392C2BCAF; Mon, 13 Apr 2026 17:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776099625; bh=1taNT22CiamjziOB4a1Po72QXWOU6A4ZwrLQB0hS3bM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u+AYIeH7//qxUKCIkxqREjbT+M/xsSPFGvKsPxdAVtd3yjC96i3aenTsP8QIfiCQa +gYG+00bCj2+nMsxoTEFosoC7kcOhFf9fXEupFyfqWzAnI2KT8Ggvxf6NQkSmLeFh9 F6Ik9o4EPihEJ8N/Th4qgp0ve4YPTIquC9NTQLwM= 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 5.10 412/491] io_uring/tctx: work around xa_store() allocation error issue Date: Mon, 13 Apr 2026 18:00:57 +0200 Message-ID: <20260413155834.453704310@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155819.042779211@linuxfoundation.org> References: <20260413155819.042779211@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 5.10-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 @@ -8524,8 +8524,19 @@ 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);