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Tue, 26 May 2026 20:26:38 -0700 (PDT) Received: from [127.0.0.1] ([116.80.91.208]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2beb58dba7bsm133826365ad.66.2026.05.26.20.26.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2026 20:26:38 -0700 (PDT) From: Cunlong Li Date: Wed, 27 May 2026 11:26:20 +0800 Subject: [PATCH] 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: quoted-printable Message-Id: <20260527-zram-v1-1-ce1acb2bfaf9@gmail.com> X-B4-Tracking: v=1; b=H4sIAFtkFmoC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIzMDUyMz3aqixFzdJANDEyPTJPNUs2QzJaDSgqLUtMwKsDHRsbW1ALPvOSp WAAAA X-Change-ID: 20260526-zram-b01425b7e6c6 To: Minchan Kim , Sergey Senozhatsky , Jens Axboe , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Christoph Hellwig , stable@vger.kernel.org, Cunlong Li X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779852395; l=1573; i=shenxiaogll@gmail.com; s=20260517; h=from:subject:message-id; bh=7NqP8wTnbRIxVIzZFbQP+alLTQXvzELVOk1InVzXOvQ=; b=rMIc9aoiEnh5ChwVz/WDhL34yOkVfP7nSmRV3FVvu4I0exZ1M9lMnRqSVW+ZJNXsgn1H9tPeZ cerOcUqZw+JCmnJWc/vNNzhiTrqiUdUtfEtbzW1nN8rRT966vG6i9zb 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; =20 - ret =3D zram_read_page(zram, page, index, bio); + ret =3D zram_read_page(zram, page, index, NULL); if (!ret) { memcpy_from_bvec(page_address(page) + offset, bvec); ret =3D zram_write_page(zram, page, index); --- base-commit: e8c2f9fdadee7cbc75134dc463c1e0d856d6e5c7 change-id: 20260526-zram-b01425b7e6c6 Best regards, --=20 Cunlong Li