CVE-2021-47496
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk39th percentile - higher than 39% of all known CVEs
Summary
In the Linux kernel's net/tls module, a flipped sign in tls_err_abort() calls leads to incorrect error handling and potential memory corruption. The fix ensures consistent negative error codes and centralizes the sign flip.
Risk Assessment
This vulnerability can cause memory corruption in TLS contexts, potentially leading to system crashes or privilege escalation.
Recommendation
Install the Linux kernel update with the fix for CVE-2021-47496. Ensure systems using kTLS are patched.
Original NVD description (English source)
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.