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bh=YVYoQXqbAhClYeVOSKCSUuE45ImToUPrk58Cjywvc/0=; b=i0of2tL3GEitwUw7w60XAWaCrkNa6jT2th2/FtjA/hQNgUZocVsouS56K0LWkdSOBJIH6i ZWZ1dLtkWCtcMAlRGPueAHacucRAuzcMagq7MrSO2NAbcpYUNJ1VOmll+YwqXUAv2b1FSR dL+wFHNxZXo/0czGtKTlcZ3PgXgQ8/Y= X-MC-Unique: SGEQ76CpPBSj1dWHZCO9hQ-1 From: Hanna Czenczek To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Czenczek , Stefan Hajnoczi , Kevin Wolf , Peter Maydell Subject: [PATCH v2] block: Fix pad_request's request restriction Date: Fri, 14 Jul 2023 10:59:38 +0200 Message-ID: <20230714085938.202730-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1689325244904100001 Content-Type: text/plain; charset="utf-8" bdrv_pad_request() relies on requests' lengths not to exceed SIZE_MAX, which bdrv_check_qiov_request() does not guarantee. bdrv_check_request32() however will guarantee this, and both of bdrv_pad_request()'s callers (bdrv_co_preadv_part() and bdrv_co_pwritev_part()) already run it before calling bdrv_pad_request(). Therefore, bdrv_pad_request() can safely call bdrv_check_request32() without expecting error, too. In effect, this patch will not change guest-visible behavior. It is a clean-up to tighten a condition to match what is guaranteed by our callers, and which exists purely to show clearly why the subsequent assertion (`assert(*bytes <=3D SIZE_MAX)`) is always true. Note there is a difference between the interfaces of bdrv_check_qiov_request() and bdrv_check_request32(): The former takes an errp, the latter does not, so we can no longer just pass &error_abort. Instead, we need to check the returned value. While we do expect success (because the callers have already run this function), an assert(ret =3D=3D 0) is not much simpler than just to return an error if it occurs, so let us handle errors by returning them up the stack now. Reported-by: Peter Maydell Fixes: 18743311b829cafc1737a5f20bc3248d5f91ee2a ("block: Collapse padded I/O vecs exceeding IOV_MAX") Signed-off-by: Hanna Czenczek --- v2: - Added paragraph to the commit message to express explicitly that this patch will not change guest-visible behavior - (No code changes) --- block/io.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/block/io.c b/block/io.c index e8293d6b26..055fcf7438 100644 --- a/block/io.c +++ b/block/io.c @@ -1710,7 +1710,11 @@ static int bdrv_pad_request(BlockDriverState *bs, int sliced_niov; size_t sliced_head, sliced_tail; =20 - bdrv_check_qiov_request(*offset, *bytes, *qiov, *qiov_offset, &error_a= bort); + /* Should have been checked by the caller already */ + ret =3D bdrv_check_request32(*offset, *bytes, *qiov, *qiov_offset); + if (ret < 0) { + return ret; + } =20 if (!bdrv_init_padding(bs, *offset, *bytes, write, pad)) { if (padded) { @@ -1723,7 +1727,7 @@ static int bdrv_pad_request(BlockDriverState *bs, &sliced_head, &sliced_tail, &sliced_niov); =20 - /* Guaranteed by bdrv_check_qiov_request() */ + /* Guaranteed by bdrv_check_request32() */ assert(*bytes <=3D SIZE_MAX); ret =3D bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov, sliced_head, *bytes); --=20 2.41.0