diff options
| author | Zack Rusin <zack.rusin@broadcom.com> | 2026-05-05 18:22:29 -0400 |
|---|---|---|
| committer | Zack Rusin <zack.rusin@broadcom.com> | 2026-07-27 11:29:24 -0400 |
| commit | 05eaa887e7b4f40fba425f8a1d7a5a8a043092a6 (patch) | |
| tree | ebf82822db2682dd550ba6fc86ce3fe0907266e5 /drivers/gpu/drm | |
| parent | f4f1db96bfd68b81053693ba53405b6f510ac16c (diff) | |
drm/vmwgfx: avoid destroy_workqueue(NULL) on vkms init failure
Two paths through vmw_vkms_init() can leave vmw->crc_workq NULL while
still leaving the rest of the driver in a state that calls
vmw_vkms_cleanup() at module unload:
1. vmw_host_get_guestinfo(GUESTINFO_VBLANK, ...) failing or
returning an oversized buffer -- the common case on hosts
without a VBLANK guestinfo entry -- early-returned before the
workqueue allocation.
2. alloc_ordered_workqueue() returning NULL on memory pressure.
vmw_vkms_cleanup() then calls destroy_workqueue(NULL), which
dereferences wq->name and panics.
Fix the first case by removing the early return: vmw->vkms_enabled
is already false on the rpci-failure path so no work will ever be
queued, and allocating the workqueue unconditionally keeps the
control flow simple. Fix the second case by guarding the cleanup
with a NULL check, since alloc_ordered_workqueue() can still fail
under low memory.
Fixes: 7b0062036c3b ("drm/vmwgfx: Implement virtual crc generation")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4.7
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Reviewed-by: Ian Forbes <ian.forbes@broadcom.com>
Link: https://patch.msgid.link/20260505222728.519626-9-zack.rusin@broadcom.com
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c index 7b8163b5e501..3d0d5dfa869f 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c @@ -206,14 +206,14 @@ vmw_vkms_init(struct vmw_private *vmw) vmw->vkms_enabled = false; ret = vmw_host_get_guestinfo(GUESTINFO_VBLANK, buffer, &buf_len); - if (ret || buf_len > max_buf_len) - return; - buffer[buf_len] = '\0'; + if (!ret && buf_len <= max_buf_len) { + buffer[buf_len] = '\0'; - ret = kstrtobool(buffer, &vmw->vkms_enabled); - if (!ret && vmw->vkms_enabled) { - ret = drm_vblank_init(&vmw->drm, VMWGFX_NUM_DISPLAY_UNITS); - vmw->vkms_enabled = (ret == 0); + ret = kstrtobool(buffer, &vmw->vkms_enabled); + if (!ret && vmw->vkms_enabled) { + ret = drm_vblank_init(&vmw->drm, VMWGFX_NUM_DISPLAY_UNITS); + vmw->vkms_enabled = (ret == 0); + } } vmw->crc_workq = alloc_ordered_workqueue("vmwgfx_crc_generator", 0); @@ -228,7 +228,8 @@ vmw_vkms_init(struct vmw_private *vmw) void vmw_vkms_cleanup(struct vmw_private *vmw) { - destroy_workqueue(vmw->crc_workq); + if (vmw->crc_workq) + destroy_workqueue(vmw->crc_workq); } bool |