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 C42FD22A7EC; Thu, 12 Dec 2024 16:36:40 +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=1734021400; cv=none; b=GAOi6OTGxfGpU08W3L0ffbduv5cqkNf2QuHVNda0aAzyFq2qHwXALRWSWpHuwtD+yuhEW49pMhhQSPetgTbGLEqZ7VmXYKntufWfT+32TEnTuyrkWm3rjxoNMq7MMNXM+5kfIaurtgnj4DcqiPId+PJtQl0jZWPnXv64aBaPHqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734021400; c=relaxed/simple; bh=PqdKa6tQRWXt/ZuKtmK0goSI3YIAIuJrG/4S70No520=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q8hOtDDrSoALSCMhuuhFCCewDv6S/Qj1kw8fSzed5n9/kGMbzmi7g4xKAE994AEj9mi7Tn86xdLV3yvWYU/rnEdnpljhZceVJwEF+xuBa+SFb+rpMq7LF9sfwe26e3kXVzI36RKjwvmgBXHmnsMw4a9mx+Fs+WaRICkogDmC2p0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=c+sfDSYQ; 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="c+sfDSYQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A82AC4CECE; Thu, 12 Dec 2024 16:36:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734021400; bh=PqdKa6tQRWXt/ZuKtmK0goSI3YIAIuJrG/4S70No520=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c+sfDSYQkpwdpmRWAdkdTsvSxq6aet54+VIIyP0jRCAkF8HjwMx1Lc7EJkKgoamcx qkTeSQbb4mkB0X1KinRnoqt7MB0abdv3wK/j2Gz2ne7irHGdzc9Fj0+L6m1dSkBR1f pFJlfihi1mI2RcktqEbLuupuDPUmipZYYlbxH/8E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com, Jens Axboe , Sasha Levin Subject: [PATCH 6.1 728/772] io_uring/tctx: work around xa_store() allocation error issue Date: Thu, 12 Dec 2024 16:01:13 +0100 Message-ID: <20241212144419.974130831@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144349.797589255@linuxfoundation.org> References: <20241212144349.797589255@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe [ Upstream commit 7eb75ce7527129d7f1fee6951566af409a37a1c4 ] 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 Signed-off-by: Sasha Levin --- io_uring/tctx.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/io_uring/tctx.c b/io_uring/tctx.c index 4324b1cf1f6af..51b05fda8e455 100644 --- a/io_uring/tctx.c +++ b/io_uring/tctx.c @@ -47,8 +47,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx, 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); -- 2.43.0