git: 57b3853cc9bb - releng/15.0 - rack: Reload the TCP stack PCB after reacquiring the inpcb lock

The branch releng/15.0 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=57b3853cc9bbe164a82844eb9a0d5196ff52a8e7

commit 57b3853cc9bbe164a82844eb9a0d5196ff52a8e7
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-06-23 21:46:17 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-06-30 02:32:57 +0000

    rack: Reload the TCP stack PCB after reacquiring the inpcb lock
    
    Malicious userspace might switch TCP stacks twice while the inpcb lock
    is dropped.  If it does so, the validation of tp->t_fb might succeed,
    but the saved pointer to the stack PCB might be invalid.  Reload it to
    avoid this problem, as BBR already does.
    
    Approved by:    so
    Security:       FreeBSD-SA-26:43.tcp
    Security:       CVE-2026-49422
    Reported by:    Maik Münch
    Reviewed by:    tuexen
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D57791
---
 sys/netinet/tcp_stacks/rack.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c
index 9bc4530afe10..462bd6c6aa0b 100644
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -24138,6 +24138,7 @@ process_opt:
 		INP_WUNLOCK(inp);
 		return (ENOPROTOOPT);
 	}
+	rack = (struct tcp_rack *)tp->t_fb_ptr;
 	if (rack->defer_options && (rack->gp_ready == 0) &&
 	    (sopt->sopt_name != TCP_DEFER_OPTIONS) &&
 	    (sopt->sopt_name != TCP_HYBRID_PACING) &&