[v1] migration/dirtyrate: Fix segmentation fault

[PATCH] migration/dirtyrate: Fix segmentation fault

Masato Imai posted 1 patch 1 week, 4 days ago

Diff against v2
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git fetch https://github.com/patchew-project/qemu tags/patchew/20240423061925.254941-1-mii@sfc.wide.ad.jp

Maintainers: Hyman Huang <yong.huang@smartx.com>, Peter Xu <peterx@redhat.com>, Fabiano Rosas <farosas@suse.de>

There is a newer version of this series

migration/dirtyrate.c | 2 ++
1 file changed, 2 insertions(+)

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[PATCH] migration/dirtyrate: Fix segmentation fault

Posted by Masato Imai 1 week, 4 days ago

When the KVM acceleration parameter is not set, executing calc_dirty_rate
with the -r option results in a segmentation fault due to accessing a
null kvm_state pointer in the kvm_dirty_rate_enabled function.
This commit adds a check for kvm_enabled to prevent segmentation faults.

Signed-off-by: Masato Imai <mii@sfc.wide.ad.jp>
---
 migration/dirtyrate.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 1d2e85746f..4c1579c6e9 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -800,6 +800,8 @@ void qmp_calc_dirty_rate(int64_t calc_time,
      * on the contrary, dirty bitmap mode is not.
      */
     if (((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) &&
+        !kvm_enabled()) ||
+        ((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) &&
         !kvm_dirty_ring_enabled()) ||
         ((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP) &&
          kvm_dirty_ring_enabled())) {
-- 
2.34.1

Re: [PATCH] migration/dirtyrate: Fix segmentation fault

Posted by Yong Huang 1 week, 4 days ago

On Tue, Apr 23, 2024 at 2:19 PM Masato Imai <mii@sfc.wide.ad.jp> wrote:

> When the KVM acceleration parameter is not set, executing calc_dirty_rate
> with the -r option results in a segmentation fault due to accessing a
> null kvm_state pointer in the kvm_dirty_rate_enabled function.
>

s/kvm_dirty_rate_enabled/kvm_dirty_ring_enabled/

This commit adds a check for kvm_enabled to prevent segmentation faults.
>
> Signed-off-by: Masato Imai <mii@sfc.wide.ad.jp>
> ---
>  migration/dirtyrate.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index 1d2e85746f..4c1579c6e9 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -800,6 +800,8 @@ void qmp_calc_dirty_rate(int64_t calc_time,
>       * on the contrary, dirty bitmap mode is not.
>       */



     if (((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) &&
> +        !kvm_enabled()) ||
> +        ((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) &&

         !kvm_dirty_ring_enabled()) ||
>          ((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP) &&

          kvm_dirty_ring_enabled())) {
>

This path may result in segmentation fault likewise, we can fix it together
by adding the following logic before this code:

    if (!kvm_enabled() &&
       (mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING ||
        mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP)) {
        error_setg(errp, ...
        return;
    }



> --
> 2.34.1
>
>
Thanks for your work,
Yong

-- 
Best regards