git: aed4c4dd9afc - stable/15 - rack: Reload the TCP stack PCB after reacquiring the inpcb lock

The branch stable/15 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=aed4c4dd9afce3059ab582315d9049544e447a93

commit aed4c4dd9afce3059ab582315d9049544e447a93
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-06-23 21:46:17 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-06-30 17:00:27 +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 219cf2758ff2..86ea34f46a05 100644
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -24136,6 +24136,7 @@ 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) &&