CVE-2021-47496

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.