CVE-2026-97993
Received
Received - Intake
vhost-vdpa Eventfd Context Use-After-Free
Vulnerability report for CVE-2026-97993, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-25
Last updated on: 2026-09-25
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
vhost-vdpa: don't install the eventfd_ctx_fdget() error in config_ctx
vhost_vdpa_set_config_call() swaps the eventfd_ctx_fdget() return value
into v->config_ctx before checking it, so on failure the field briefly
holds an ERR_PTR:
ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
swap(ctx, v->config_ctx);
if (!IS_ERR_OR_NULL(ctx))
eventfd_ctx_put(ctx);
if (IS_ERR(v->config_ctx)) {
long ret = PTR_ERR(v->config_ctx);
v->config_ctx = NULL;
return ret;
}
Commit 0bde59c1723a ("vhost-vdpa: set v->config_ctx to NULL if
eventfd_ctx_fdget() fails") added that clearing, and spelled out the
invariant the rest of the file relies on: "we consider 'v->config_ctx'
valid if it is not NULL". The window between the swap and the clearing
still breaks it. vhost_vdpa_config_cb() only tests for NULL, so a config
interrupt delivered inside the window hands the ERR_PTR to
eventfd_signal().
Check the fd before installing it instead. That closes the window and
matches how vhost_vring_ioctl() handles the same failure for the vq call
fd.
It also stops a rejected fd from tearing down a config interrupt that was
working: until now the swap replaced the live context and put it, so
after an EBADF the device silently stopped delivering config interrupts
until userspace installed a new fd.
CVSS Scores
EPSS Scores
| Probability: | |
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
