In the Linux kernel, the following vulnerability has been resolved:

drm/hyperv: validate VMBus packet size in receive callback

hyperv_receive_sub() reads msg->vid_hdr.type and dispatches into one
of four message-type branches without knowing how many bytes the host
wrote into hv->recv_buf. The completion path then runs
memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE), so the consumer that
wakes on wait_for_completion_timeout() can read up to 16 KiB of
residue from a prior message as if it were the response payload.

Pass bytes_recvd into hyperv_receive_sub() and reject any packet that
does not cover the pipe + synthvid header. A single switch on
msg->vid_hdr.type then computes the type-specific payload size: the
three completion-driving types (SYNTHVID_VERSION_RESPONSE,
SYNTHVID_RESOLUTION_RESPONSE, SYNTHVID_VRAM_LOCATION_ACK) fall through
to a shared exit that requires that size before memcpy/complete, while
SYNTHVID_FEATURE_CHANGE validates its own payload and returns before
reading is_dirt_needed. Unknown types are dropped.

SYNTHVID_RESOLUTION_RESPONSE is variable length: the host fills
resolution_count entries, not the full SYNTHVID_MAX_RESOLUTION_COUNT
array. Validate the fixed prefix first so resolution_count can be
read, bound it against the array, then require only the count-sized
array, so the shorter responses the host actually sends are accepted.

Only run the sub-handler when vmbus_recvpacket() returned success. The
memcpy length is bytes_recvd, which is bounded by VMBUS_MAX_PACKET_SIZE
only on a successful receive; on -ENOBUFS vmbus_recvpacket() instead
reports the required length, which can exceed hv->recv_buf, so copying
bytes_recvd would read and write past the 16 KiB buffers. Gating on the
success return keeps the copy bounded. The nonzero-return path is itself
a malformed-message case and is now logged rather than silently skipped;
channel recovery is not attempted.

Rejected packets are reported via drm_err_ratelimited() rather than
silently dropped, matching the CoCo-hardened pattern in
hv_kvp_onchannelcallback().

https://git.kernel.org/stable/c/049a6b474823049fe60212f25f26e4b30f44ee8f

https://git.kernel.org/stable/c/164dc7bf17609340233c6bf4f66bb7c7008a0511

https://git.kernel.org/stable/c/57d5d697642e05d5dd2d40660817765943dd709f

https://git.kernel.org/stable/c/588c84b461393ff1998ac7b97b04f953f642e0df

https://git.kernel.org/stable/c/7f87763f47a3c22fb50265a00619ef10f2394b18

https://git.kernel.org/stable/c/c8974d96b6a5496f33dc69a3ce28a7bf5078def4

https://git.kernel.org/stable/c/f5251226551bfec98c4705641b6f94ff1f238d91

[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"57d5d697642e05d5dd2d40660817765943dd709f","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"f5251226551bfec98c4705641b6f94ff1f238d91","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"049a6b474823049fe60212f25f26e4b30f44ee8f","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"588c84b461393ff1998ac7b97b04f953f642e0df","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"164dc7bf17609340233c6bf4f66bb7c7008a0511","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"c8974d96b6a5496f33dc69a3ce28a7bf5078def4","versionType":"git","status":"affected"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","lessThan":"7f87763f47a3c22fb50265a00619ef10f2394b18","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"5.14","status":"affected"},{"version":"0","lessThan":"5.14","versionType":"semver","status":"unaffected"},{"version":"5.15.210","lessThanOrEqual":"5.15.*","versionType":"semver","status":"unaffected"},{"version":"6.1.176","lessThanOrEqual":"6.1.*","versionType":"semver","status":"unaffected"},{"version":"6.6.143","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.93","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.35","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.0.12","lessThanOrEqual":"7.0.*","versionType":"semver","status":"unaffected"},{"version":"7.1","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]