From: Zack Rusin <zackr@vmware.com>
To: <dri-devel@lists.freedesktop.org>
Cc: Martin Krastev <krastevm@vmware.com>
Subject: [PATCH 7/9] drm/vmwgfx: Refactor vmw_mksstat_remove_ioctl to expect pgid match with vmw_mksstat_add_ioctl to authorise removal.
Date: Wed, 9 Jun 2021 13:23:05 -0400 [thread overview]
Message-ID: <20210609172307.131929-8-zackr@vmware.com> (raw)
In-Reply-To: <20210609172307.131929-1-zackr@vmware.com>
From: Martin Krastev <krastevm@vmware.com>
Original vmw_mksstat_remove_ioctl expected pid to match the corresponding vmw_mksstat_add_ioctl.
That made impossible en-masse removals by one pid, which is a valid use case, so pid match was
discarded. Current change enforces a broader pgid match as a form of protection from arbitrary
processes interrupting an ongoing mks-guest-stats.
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Martin Krastev <krastevm@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
---
drivers/gpu/drm/vmwgfx/vmwgfx_msg.c | 32 ++++++++++++-----------------
1 file changed, 13 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
index 12df4c634075..74a3f09ad664 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
@@ -1111,7 +1111,7 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
hypervisor_ppn_add((PPN64)page_to_pfn(page));
dev_priv->mksstat_user_pages[slot] = page;
- atomic_set(&dev_priv->mksstat_user_pids[slot], current->pid);
+ atomic_set(&dev_priv->mksstat_user_pids[slot], task_pgrp_vnr(current));
arg->id = slot;
@@ -1158,37 +1158,31 @@ int vmw_mksstat_remove_ioctl(struct drm_device *dev, void *data,
struct vmw_private *const dev_priv = vmw_priv(dev);
const size_t slot = arg->id;
- pid_t pid0;
+ pid_t pgid, pid;
if (slot >= ARRAY_SIZE(dev_priv->mksstat_user_pids))
return -EINVAL;
DRM_DEV_INFO(dev->dev, "pid=%d arg.id=%lu\n", current->pid, slot);
- pid0 = atomic_read(&dev_priv->mksstat_user_pids[slot]);
+ pgid = task_pgrp_vnr(current);
+ pid = atomic_cmpxchg(&dev_priv->mksstat_user_pids[slot], pgid, MKSSTAT_PID_RESERVED);
- if (!pid0)
+ if (!pid)
return 0;
- if (pid0 != MKSSTAT_PID_RESERVED) {
- const pid_t pid1 = atomic_cmpxchg(&dev_priv->mksstat_user_pids[slot], pid0, MKSSTAT_PID_RESERVED);
+ if (pid == pgid) {
+ struct page *const page = dev_priv->mksstat_user_pages[slot];
- if (!pid1)
- return 0;
-
- if (pid1 == pid0) {
- struct page *const page = dev_priv->mksstat_user_pages[slot];
+ BUG_ON(!page);
- BUG_ON(!page);
-
- dev_priv->mksstat_user_pages[slot] = NULL;
- atomic_set(&dev_priv->mksstat_user_pids[slot], 0);
+ dev_priv->mksstat_user_pages[slot] = NULL;
+ atomic_set(&dev_priv->mksstat_user_pids[slot], 0);
- hypervisor_ppn_remove((PPN64)page_to_pfn(page));
+ hypervisor_ppn_remove((PPN64)page_to_pfn(page));
- vmw_mksstat_cleanup_descriptor(page);
- return 0;
- }
+ vmw_mksstat_cleanup_descriptor(page);
+ return 0;
}
return -EAGAIN;
--
2.30.2
next prev parent reply other threads:[~2021-06-09 17:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 17:22 [PATCH 0/9] Adding support for mks-stats and some cleanups/fixes Zack Rusin
2021-06-09 17:22 ` [PATCH 1/9] drm/vmwgfx: Simplify devcaps code Zack Rusin
2021-06-09 17:23 ` [PATCH 2/9] drm/vmwgfx: Introduce VMware mks-guest-stats Zack Rusin
2021-06-09 17:23 ` [PATCH 3/9] drm/vmwgfx: Fix subresource updates with new contexts Zack Rusin
2021-06-10 6:49 ` Thomas Hellström (Intel)
2021-06-10 16:59 ` Zack Rusin
2021-06-09 17:23 ` [PATCH 4/9] drm/vmwgfx: Fix some static checker warnings Zack Rusin
2021-06-09 17:23 ` [PATCH 5/9] drm/vmwgfx: remove code that was using physical page addresses Zack Rusin
2021-06-09 17:23 ` [PATCH 6/9] drm/vmwgfx: inline access to the pages from the piter Zack Rusin
2021-06-09 17:23 ` Zack Rusin [this message]
2021-06-09 17:23 ` [PATCH 8/9] drm/vmwgfx: Remove vmw_chipset Zack Rusin
2021-06-09 17:23 ` [PATCH 9/9] drm/vmwgfx: Fix implicit declaration error Zack Rusin
2021-06-09 17:24 ` Christian König
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