git: e3373e0a74f1 - stable/15 - MAC/do: find_conf(): Turn an MPASS() into a KASSERT()

The branch stable/15 has been updated by olce:

URL: https://cgit.FreeBSD.org/src/commit/?id=e3373e0a74f1537db947211ac5023f68d6a338ce

commit e3373e0a74f1537db947211ac5023f68d6a338ce
Author:     Olivier Certner <olce@FreeBSD.org>
AuthorDate: 2026-04-27 12:16:46 +0000
Commit:     Olivier Certner <olce@FreeBSD.org>
CommitDate: 2026-06-29 19:23:42 +0000

    MAC/do: find_conf(): Turn an MPASS() into a KASSERT()
    
    Turn the pre-existing comment into an assertion message, with an update
    following the introduction of the "executable paths" feature.
    
    Explain in a comment why this situation cannot happen.
    
    Without INVARIANTS, such a situation would cause an immediate panic()
    (NULL is dereferenced in the next iteration of the loop), so leave the
    check under INVARIANTS only.
    
    Reviewed by:    bapt
    MFC after:      1 month
    Sponsored by:   The FreeBSD Foundation
    Pull Request:   https://ron-dev.freebsd.org/FreeBSD/src/pulls/38
    
    (cherry picked from commit cf942ac9e967055286a7076bf76e9a62e1d22d8f)
---
 sys/security/mac_do/mac_do.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sys/security/mac_do/mac_do.c b/sys/security/mac_do/mac_do.c
index bef29badc5ba..0b224a24e0a7 100644
--- a/sys/security/mac_do/mac_do.c
+++ b/sys/security/mac_do/mac_do.c
@@ -1186,7 +1186,15 @@ find_conf(struct prison *const pr, struct prison **const aprp)
 		prison_unlock(cpr);
 
 		ppr = cpr->pr_parent;
-		MPASS(ppr != NULL); /* prison0 always has rules. */
+		/*
+		 * 'prison0' normally always have a mac_do(4) configuration
+		 * because we installed one on module load/activation and
+		 * nothing can destroy it as 'prison0' is not a regular jail and
+		 * the 'mac.do' parameter cannot be set to 'inherit' on it,
+		 * which is the only way to clear an existing configuration.
+		 */
+		KASSERT(ppr != NULL,
+		    ("MAC/do: 'prison0' must always have a configuration."));
 		cpr = ppr;
 	}