linux-kernel - [PATCH AUTOSEL 5.4 23/31] block: prevent an integer overflow in bvec_try_merge_hw

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Message-ID: <20240116200310.259340-23-sashal@kernel.org>
Date: Tue, 16 Jan 2024 15:02:32 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Christoph Hellwig <hch@....de>,
	Johannes Thumshirn <johannes.thumshirn@....com>,
	Jens Axboe <axboe@...nel.dk>,
	Sasha Levin <sashal@...nel.org>,
	linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 23/31] block: prevent an integer overflow in bvec_try_merge_hw_page

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

[ Upstream commit 3f034c374ad55773c12dd8f3c1607328e17c0072 ]

Reordered a check to avoid a possible overflow when adding len to bv_len.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@....com>
Link: https://lore.kernel.org/r/20231204173419.782378-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/bio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index 08dbdc32ceaa..17d64539819e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -710,7 +710,7 @@ static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
 
 	if ((addr1 | mask) != (addr2 | mask))
 		return false;
-	if (bv->bv_len + len > queue_max_segment_size(q))
+	if (len > queue_max_segment_size(q) - bv->bv_len)
 		return false;
 	return __bio_try_merge_page(bio, page, len, offset, same_page);
 }
-- 
2.43.0