Re: [syzbot] [mptcp?] general protection fault in proc_scheduler

Hi Eric,

On 05/01/2025 17:52, Eric Dumazet wrote:

On Sun, Jan 5, 2025 at 12:29 PM Al Viro [off-list ref] wrote:

quoted

On Sun, Jan 05, 2025 at 09:32:36AM +0100, Eric Dumazet wrote:

quoted

According to grep, we have many other places directly reading
current->nsproxy->net_ns
For instance in net/sctp/sysctl.c
Should we change them all ?

Depends - do you want their contents match the netns of opener (as,
AFAICS, for ipv4 sysctls) or that of the reader?

I am only worried that a malicious user could crash the host with
current kernels,
not about this MPTP crash, but all unaware users of current->nsproxy
in sysctl handlers.

Back to MPTCP :

Using the convention used in other mptcp sysctls like (enabled,
add_addr_timeout,
checksum_enabled, allow_join_initial_addr_port...) is better for consistency.

Indeed, I can do the modifications to stop using current->nsproxy in
MPTCP. I can do the same in SCTP.

Do you plan to send your patch modifying proc_sysctl.c? It is just to
know if I should mark my patches as fixes, and split them to ease the
backports -- each helper using current->nsproxy has been introduced in
different commits -- or if I can send them to net-next instead.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.