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74 lines
3.1 KiB
74 lines
3.1 KiB
1 year ago
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From 547f6bf93734f7c13675eebb93273ef2273f7c31 Mon Sep 17 00:00:00 2001
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From: Hanna Czenczek <hreitz@redhat.com>
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Date: Fri, 14 Jul 2023 10:59:38 +0200
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Subject: [PATCH 5/9] block: Fix pad_request's request restriction
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RH-Author: Hanna Czenczek <hreitz@redhat.com>
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RH-MergeRequest: 189: block: Split padded I/O vectors exceeding IOV_MAX
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RH-Bugzilla: 2174676
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [5/5] e8abc0485f6e0608a1ec55143ff40a14d273dfc8 (hreitz/qemu-kvm-c-9-s)
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bdrv_pad_request() relies on requests' lengths not to exceed SIZE_MAX,
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which bdrv_check_qiov_request() does not guarantee.
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bdrv_check_request32() however will guarantee this, and both of
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bdrv_pad_request()'s callers (bdrv_co_preadv_part() and
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bdrv_co_pwritev_part()) already run it before calling
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bdrv_pad_request(). Therefore, bdrv_pad_request() can safely call
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bdrv_check_request32() without expecting error, too.
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In effect, this patch will not change guest-visible behavior. It is a
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clean-up to tighten a condition to match what is guaranteed by our
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callers, and which exists purely to show clearly why the subsequent
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assertion (`assert(*bytes <= SIZE_MAX)`) is always true.
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Note there is a difference between the interfaces of
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bdrv_check_qiov_request() and bdrv_check_request32(): The former takes
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an errp, the latter does not, so we can no longer just pass
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&error_abort. Instead, we need to check the returned value. While we
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do expect success (because the callers have already run this function),
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an assert(ret == 0) is not much simpler than just to return an error if
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it occurs, so let us handle errors by returning them up the stack now.
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Reported-by: Peter Maydell <peter.maydell@linaro.org>
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Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
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Message-id: 20230714085938.202730-1-hreitz@redhat.com
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Fixes: 18743311b829cafc1737a5f20bc3248d5f91ee2a
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("block: Collapse padded I/O vecs exceeding IOV_MAX")
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Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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block/io.c | 8 ++++++--
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1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/block/io.c b/block/io.c
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index 4e8e90208b..807c9fb720 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -1708,7 +1708,11 @@ static int bdrv_pad_request(BlockDriverState *bs,
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int sliced_niov;
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size_t sliced_head, sliced_tail;
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- bdrv_check_qiov_request(*offset, *bytes, *qiov, *qiov_offset, &error_abort);
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+ /* Should have been checked by the caller already */
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+ ret = bdrv_check_request32(*offset, *bytes, *qiov, *qiov_offset);
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+ if (ret < 0) {
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+ return ret;
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+ }
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if (!bdrv_init_padding(bs, *offset, *bytes, write, pad)) {
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if (padded) {
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@@ -1721,7 +1725,7 @@ static int bdrv_pad_request(BlockDriverState *bs,
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&sliced_head, &sliced_tail,
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&sliced_niov);
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- /* Guaranteed by bdrv_check_qiov_request() */
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+ /* Guaranteed by bdrv_check_request32() */
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assert(*bytes <= SIZE_MAX);
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ret = bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov,
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sliced_head, *bytes);
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--
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2.39.3
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