linux-kernel - [PATCH AUTOSEL 6.10 1/3] block: don't call bio_uninit from bio

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Message-ID: <20240730124222.3083443-1-sashal@kernel.org>
Date: Tue, 30 Jul 2024 08:42:19 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Christoph Hellwig <hch@....de>,
	"Martin K . Petersen" <martin.petersen@...cle.com>,
	Jens Axboe <axboe@...nel.dk>,
	Sasha Levin <sashal@...nel.org>,
	linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 6.10 1/3] block: don't call bio_uninit from bio_endio

From: Christoph Hellwig <hch@....de>

[ Upstream commit bf4c89fc8797f5c0964a0c3d561fbe7e8483b62f ]

Commit b222dd2fdd53 ("block: call bio_uninit in bio_endio") added a call
to bio_uninit in bio_endio to work around callers that use bio_init but
fail to call bio_uninit after they are done to release the resources.
While this is an abuse of the bio_init API we still have quite a few of
those left.  But this early uninit causes a problem for integrity data,
as at least some users need the bio_integrity_payload.  Right now the
only one is the NVMe passthrough which archives this by adding a special
case to skip the freeing if the BIP_INTEGRITY_USER flag is set.

Sort this out by only putting bi_blkg in bio_endio as that is the cause
of the actual leaks - the few users of the crypto context and integrity
data all properly call bio_uninit, usually through bio_put for
dynamically allocated bios.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Martin K. Petersen <martin.petersen@...cle.com>
Link: https://lore.kernel.org/r/20240702151047.1746127-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/bio.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index e9e809a63c597..c7a4bc05c43e7 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1630,8 +1630,18 @@ void bio_endio(struct bio *bio)
 		goto again;
 	}

-	/* release cgroup info */
-	bio_uninit(bio);
+#ifdef CONFIG_BLK_CGROUP
+	/*
+	 * Release cgroup info.  We shouldn't have to do this here, but quite
+	 * a few callers of bio_init fail to call bio_uninit, so we cover up
+	 * for that here at least for now.
+	 */
+	if (bio->bi_blkg) {
+		blkg_put(bio->bi_blkg);
+		bio->bi_blkg = NULL;
+	}
+#endif
+
 	if (bio->bi_end_io)
 		bio->bi_end_io(bio);
 }
-- 
2.43.0