From: Sven Eckelmann <sven@narfation.org>
Date: Mon, 2 Aug 2021 18:24:44 +0200
Subject: debugfs: Return error during {full/open}_proxy_open() on rmmod
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Patch-mainline: v5.15-rc1
Git-commit: 112cedc8e600b668688eb809bf11817adec58ddc
References: bsc#1173746

If a kernel module gets unloaded then it printed report about a leak before
commit 275678e7a9be ("debugfs: Check module state before warning in
{full/open}_proxy_open()"). An additional check was added in this commit to
avoid this printing. But it was forgotten that the function must return an
error in this case because it was not actually opened.

As result, the systems started to crash or to hang when a module was
unloaded while something was trying to open a file.

Fixes: 275678e7a9be ("debugfs: Check module state before warning in {full/open}_proxy_open()")
Cc: Taehee Yoo <ap420073@gmail.com>
Reported-by: Mário Lopes <ml@simonwunderlich.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Link: https://lore.kernel.org/r/20210802162444.7848-1-sven@narfation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 fs/debugfs/file.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -154,8 +154,10 @@ static int open_proxy_open(struct inode
 	if (!fops_get(real_fops)) {
 #ifdef CONFIG_MODULES
 		if (real_fops->owner &&
-		    real_fops->owner->state == MODULE_STATE_GOING)
+		    real_fops->owner->state == MODULE_STATE_GOING) {
+			r = -ENXIO;
 			goto out;
+		}
 #endif
 
 		/* Huh? Module did not clean up after itself at exit? */
@@ -284,8 +286,10 @@ static int full_proxy_open(struct inode
 	if (!fops_get(real_fops)) {
 #ifdef CONFIG_MODULES
 		if (real_fops->owner &&
-		    real_fops->owner->state == MODULE_STATE_GOING)
+		    real_fops->owner->state == MODULE_STATE_GOING) {
+			r = -ENXIO;
 			goto out;
+		}
 #endif
 
 		/* Huh? Module did not cleanup after itself at exit? */