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 85C9913B58A; Sun, 1 Mar 2026 01:32:38 +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=1772328758; cv=none; b=mTyB/ZxcCMwP+uIQ0fM43A4OqKnTdZMG0Qa8kh25bzbmScRvoWxevnbLP7roVe9lgWq58EFAohC96h/1maUDZQDNRjAo7jpCgxvW4OjTr569AEftOW9sMMHgvQF3yEfbgee4sLbaq0oXD9Ob9f4dywqsa4Na/BhheRaWGKnHOHI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772328758; c=relaxed/simple; bh=KH3qxqzi9XQ9F+p84tRvdsjBiT1ixpg/UFT+2Sl7yOI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=D2owO0C3OQtSrK/kSaRArzh+V0XJTq9DfIkt+dHf+gCBQ+gTWUng7v1gqBU5Au/k5gQlwcKtjbCd0VbaNujBklaAcppuBQqtOz/SrwrrSxMFqAMMGahIC4CSZTLuGSWGiQbfqX0S2DSNN56pmnuDFOU/ViUSh2O6ohxjBnhIFFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EDRWcd5S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EDRWcd5S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FFDFC19421; Sun, 1 Mar 2026 01:32:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772328758; bh=KH3qxqzi9XQ9F+p84tRvdsjBiT1ixpg/UFT+2Sl7yOI=; h=From:To:Cc:Subject:Date:From; b=EDRWcd5Sq3Mq9yBxFoSg76a+rtsoXmsS6l73pJ80Xi3TtGl2gyQGpgYVzR3qdjh5y clCtgVrI8dmkkwwLCv1sbs+fA1Yfcmciat0TkO0BX+Y7RWFZiasSKc/6qC+0Bu8H4P y5UXvaC/uT6tOarA9sQx4uEAOPwpx6gabpWvzGYpLhE99janrzR1I35fDOFk41TQfS f4Cm2l9JkntjqlPrbopEkLrawXmH74b6j5/qg+LkU5/ebRK6IE7m3hKQdKRcTq9/L/ 95sRXruasWgf3vfqPGXwJgvAQOrOU32Djic2IKZrPjn32heHYSGXJlzDFD3DGM+xlf J2UQLYNow1PZA== From: Sasha Levin To: stable@vger.kernel.org, mliang@purestorage.com Cc: Mohamed Khalfella , Mikulas Patocka , dm-devel@lists.linux.dev Subject: FAILED: Patch "dm: clear cloned request bio pointer when last clone bio completes" failed to apply to 6.6-stable tree Date: Sat, 28 Feb 2026 20:32:35 -0500 Message-ID: <20260301013236.1691598-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-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 . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From fb8a6c18fb9a6561f7a15b58b272442b77a242dd Mon Sep 17 00:00:00 2001 From: Michael Liang Date: Fri, 9 Jan 2026 15:52:54 -0700 Subject: [PATCH] dm: clear cloned request bio pointer when last clone bio completes Stale rq->bio values have been observed to cause double-initialization of cloned bios in request-based device-mapper targets, leading to use-after-free and double-free scenarios. One such case occurs when using dm-multipath on top of a PCIe NVMe namespace, where cloned request bios are freed during blk_complete_request(), but rq->bio is left intact. Subsequent clone teardown then attempts to free the same bios again via blk_rq_unprep_clone(). The resulting double-free path looks like: nvme_pci_complete_batch() nvme_complete_batch() blk_mq_end_request_batch() blk_complete_request() // called on a DM clone request bio_endio() // first free of all clone bios ... rq->end_io() // end_clone_request() dm_complete_request(tio->orig) dm_softirq_done() dm_done() dm_end_request() blk_rq_unprep_clone() // second free of clone bios Fix this by clearing the clone request's bio pointer when the last cloned bio completes, ensuring that later teardown paths do not attempt to free already-released bios. Signed-off-by: Michael Liang Reviewed-by: Mohamed Khalfella Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org --- drivers/md/dm-rq.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 5e08546696145..923252fb57aec 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -109,14 +109,21 @@ static void end_clone_bio(struct bio *clone) */ tio->completed += nr_bytes; + if (!is_last) + return; + /* + * At this moment we know this is the last bio of the cloned request, + * and all cloned bios have been released, so reset the clone request's + * bio pointer to avoid double free. + */ + tio->clone->bio = NULL; + exit: /* * Update the original request. * Do not use blk_mq_end_request() here, because it may complete * the original request before the clone, and break the ordering. */ - if (is_last) - exit: - blk_update_request(tio->orig, BLK_STS_OK, tio->completed); + blk_update_request(tio->orig, BLK_STS_OK, tio->completed); } static struct dm_rq_target_io *tio_from_request(struct request *rq) -- 2.51.0