Vulnerability CVE-2024-42246
Published: 2024-08-07

Description:
In the Linux kernel, the following vulnerability has been resolved:

net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket

When using a BPF program on kernel_connect(), the call can return -EPERM. This
causes xs_tcp_setup_socket() to loop forever, filling up the syslog and causing
the kernel to potentially freeze up.

Neil suggested:

This will propagate -EPERM up into other layers which might not be ready
to handle it. It might be safer to map EPERM to an error we would be more
likely to expect from the network system - such as ECONNREFUSED or ENETDOWN.

ECONNREFUSED as error seems reasonable. For programs setting a different error
can be out of reach (see handling in 4fbac77d2d09) in particular on kernels
which do not have f10d05966196 ("bpf: Make BPF_PROG_RUN_ARRAY return -err
instead of allow boolean"), thus given that it is better to simply remap for
consistent behavior. UDP does handle EPERM in xs_udp_send_request().

 References:
https://git.kernel.org/stable/c/f2431e7db0fe0daccb2f06bb0d23740affcd2fa6
https://git.kernel.org/stable/c/d6c686c01c5f12ff8f7264e0ddf71df6cb0d4414
https://git.kernel.org/stable/c/f388cfd913a2b96c05339a335f365795db1b36b6
https://git.kernel.org/stable/c/626dfed5fa3bfb41e0dffd796032b555b69f9cde
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