CVE-2026-97952

Status: UPDATED  |  Advisory ID: CVE-2026-97952

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

sunvdc: unmap LDC cookies when the descriptor send fails

__send_request() maps the request's pages into the LDC channel's map

table (ldc_map_sg()), fills in the descriptor and marks it

VIO_DESC_READY before ringing the doorbell via __vdc_tx_trigger().

When the trigger fails, the error path only prints a message: the

descriptor stays READY and the cookies are never unmapped. The

mapping is normally released in vdc_end_one() when the peer completes

the descriptor - but a descriptor whose doorbell was never sent will

never complete, and since dr->prod is not advanced on failure, the

reset path (vdc_requeue_inflight(), which walks [cons, prod)) never

visits it either. The map table entries are leaked permanently.

Since commit a11f6ca9aef9 ("sunvdc: Do not spin in an infinite loop

when vio_ldc_send() returns EAGAIN") trigger failures occur in

practice under load, so every resulting I/O error also leaks one

request's worth of entries from the fixed-size (8192 entries per

channel) map table. Because the allocator hands out contiguous

ranges, fragmentation makes large multi-segment requests fail first

as the table drains, until ldc_map_sg() fails permanently and the

disk is dead until reboot.

It also makes any retry-based recovery unusable: requeuing the

request on -EAGAIN remaps the pages on every attempt, overwriting

desc->cookies and orphaning the previous mapping, so the table

drains at the retry rate. This is the memory exhaustion observed

when the requeue approach was first tested in October 2025.

Roll back on failure: unmap the cookies, mark the descriptor FREE

again and clear the request entry. If the trigger failed with

-ENOTCONN, __vdc_tx_trigger() has already reset the port, which

tears down and reallocates both the dring and the LDC channel

including its map table - nothing to roll back, and the stale

descriptor must not be touched. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References