git: 72b114169bd5 - main - linker: Avoid invoking eventhandlers on incompletely loaded files

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=72b114169bd56ec157d746a2df87b3a4617065b3

commit 72b114169bd56ec157d746a2df87b3a4617065b3
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2025-11-26 18:15:48 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2025-12-01 14:19:18 +0000

    linker: Avoid invoking eventhandlers on incompletely loaded files
    
    We do not invoke the kld_load eventhandler until after the file is fully
    linked, so don't invoke the kld_unload_try or kld_unload event handlers
    unless the file is fully linked either.
    
    In my case, the dtrace SDT kld_unload_try handler was running before
    relocations were processed against the file, and that caused problems
    when sdt_kld_unload_probes() accesses elements of a linker set.
    
    Move the kld_unload handler invocation earlier, to after sysuninits have
    been run.  This is a bit more consistent with the kld_load handler.
    
    PR:             291238
    Reviewed by:    imp, emaste, kib
    MFC after:      2 weeks
    Differential Revision:  https://reviews.freebsd.org/D53938
---
 sys/kern/kern_linker.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/sys/kern/kern_linker.c b/sys/kern/kern_linker.c
index e2f63cbc0c5a..9559b5233a3e 100644
--- a/sys/kern/kern_linker.c
+++ b/sys/kern/kern_linker.c
@@ -703,9 +703,11 @@ linker_file_unload(linker_file_t file, int flags)
 
 	/* Give eventhandlers a chance to prevent the unload. */
 	error = 0;
-	EVENTHANDLER_INVOKE(kld_unload_try, file, &error);
-	if (error != 0)
-		return (EBUSY);
+	if ((file->flags & LINKER_FILE_LINKED) != 0) {
+		EVENTHANDLER_INVOKE(kld_unload_try, file, &error);
+		if (error != 0)
+			return (EBUSY);
+	}
 
 	KLD_DPF(FILE, ("linker_file_unload: file is unloading,"
 	    " informing modules\n"));
@@ -768,10 +770,12 @@ linker_file_unload(linker_file_t file, int flags)
 	 * Don't try to run SYSUNINITs if we are unloaded due to a
 	 * link error.
 	 */
-	if (file->flags & LINKER_FILE_LINKED) {
+	if ((file->flags & LINKER_FILE_LINKED) != 0) {
 		file->flags &= ~LINKER_FILE_LINKED;
 		linker_file_unregister_sysctls(file);
 		linker_file_sysuninit(file);
+		EVENTHANDLER_INVOKE(kld_unload, file->filename, file->address,
+		    file->size);
 	}
 	TAILQ_REMOVE(&linker_files, file, link);
 
@@ -788,9 +792,6 @@ linker_file_unload(linker_file_t file, int flags)
 
 	LINKER_UNLOAD(file);
 
-	EVENTHANDLER_INVOKE(kld_unload, file->filename, file->address,
-	    file->size);
-
 	if (file->filename) {
 		free(file->filename, M_LINKER);
 		file->filename = NULL;