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Tue, 26 May 2026 21:49:31 -0700 (PDT) From: Cunlong Li Date: Wed, 27 May 2026 12:49:24 +0800 Subject: [PATCH v2 1/2] zram: fix use-after-free in zram_bvec_write_partial() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260527-zram-v2-1-2fb84b054b5c@gmail.com> References: <20260527-zram-v2-0-2fb84b054b5c@gmail.com> In-Reply-To: <20260527-zram-v2-0-2fb84b054b5c@gmail.com> To: Minchan Kim , Sergey Senozhatsky , Jens Axboe , Andrew Morton Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Cunlong Li , stable@vger.kernel.org X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779857366; l=1429; i=shenxiaogll@gmail.com; s=20260517; h=from:subject:message-id; bh=GYq7eClao3GaV9lgjcsADvNLW1hhn25v8rqXYSyuj3E=; b=y0NCB/JE8egqDA7ZvcgiKHXXTPhJDt3eJNcyH9vjqfcf2urXXxuO/7LuiX3+8OQB5bskhQHGQ e9j1YvGYcbyBEJhvACdZy6pB4TiDjVceAUvbcQ9UF8MJErpnJDy5PYO X-Developer-Key: i=shenxiaogll@gmail.com; a=ed25519; pk=SKFifnqPdsvsjuhUiq+Y9vtCdhyZ/LrRcfYn8eRq6AE= zram_read_page() picks the sync or async backing device read path based on whether the parent bio is NULL. zram_bvec_write_partial() passes its parent bio down, so for ZRAM_WB slots the read is dispatched asynchronously and zram_read_page() returns 0 while the bio is still in flight. The caller then runs memcpy_from_bvec(), zram_write_page() and __free_page() on the buffer, leaving the async read to write into a freed page. zram_bvec_read_partial() was switched to NULL in commit 4e3c87b9421d ("zram: fix synchronous reads") for the same reason; the write_partial counterpart was missed. Fixes: 4e3c87b9421d ("zram: fix synchronous reads") Cc: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Cunlong Li --- drivers/block/zram/zram_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index aebc710f0d6a..b23a8bbb687c 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -2333,7 +2333,7 @@ static int zram_bvec_write_partial(struct zram *zram, struct bio_vec *bvec, if (!page) return -ENOMEM; - ret = zram_read_page(zram, page, index, bio); + ret = zram_read_page(zram, page, index, NULL); if (!ret) { memcpy_from_bvec(page_address(page) + offset, bvec); ret = zram_write_page(zram, page, index); -- 2.30.2