Medium [CVE-2026-63821] fix memory leaks on USB write failures
This medium-severity Red Hat Linux advisory covers CVE-2026-63821 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: wifi: rtw88: usb: fix memory leaks on USB write failures When rtw_usb_write_port() fails to submit a USB Request Block (URB) (e.g., due to device disconnect or ENOMEM), the completion callback is never executed.
Currently, the driver ignores the return value of rtw_usb_write_port() in rtw_usb_write_data() and rtw_usb_tx_agg_skb(). Because these functions rely on the completion callback to free the socket buffers (skbs) and the transaction control block (txcb), a submission failure results in: 1.
A memory leak of the allocated skb in rtw_usb_write_data(). 2.
A memory leak of the txcb structure and all aggregated skbs in rtw_usb_tx_agg_skb(). If it fails, explicitly free the skb in rtw_usb_write_data(), and properly purge the tx_ack_queue and free the txcb in rtw_usb_tx_agg_skb().
The issue was discovered in practice during device disconnect/reconnect scenarios and memory pressure conditions. Tested by verifying normal TX operation continues after the fix without regressions.
When the `rtw_usb_write_port()` function fails to submit a USB Request Block (URB), such as during a device disconnect or out of memory conditions, the system does not properly free allocated memory. This oversight leads to memory leaks of socket buffers and transaction control blocks.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
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