CVE-2021-47496: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.5% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: net/tls: Fix flipped sign in tls_err_abort() calls sk->sk_err appears to expect a positive value, a convention that ktls doesn't always follow and that leads to memory corruption in other code. For instance, [kworker] tls_encrypt_done(..., err=<negative error from crypto request>) tls_err_abort(.., err) sk->sk_err = err; [task] splice_from_pipe_feed ... tls_sw_do_sendpage if (sk->sk_err) { ret = -sk->sk_err; // ret is positive splice_from_pipe_feed (continued) ret = actor(...) // ret is still positive and interpreted as bytes // written, resulting in underflow of buf->len and // sd->len, leading to huge buf->offset and bogus // addresses computed in later calls to actor() Fix all tls_err_abort() callers to pass a negative error code consistently and centralize the error-prone sign flip there, throwing in a warning to catch future misuse and uninlining the function so it really does only warn once.

Affected products

• Linux Linux Kernel: from 4.17, before 5.4.157 (fixed in 5.4.157); from 5.5, before 5.10.77 (fixed in 5.10.77); from 5.11, before 5.14.16 (fixed in 5.14.16); version 5.15 only

Published 2024-05-22. Last modified 2026-08-04.