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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Tiezhu Yang <yangtiezhu@loongson.cn>,
        Andrew Morton <akpm@linux-foundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.8 205/232] lib/test_lockup.c: fix return value of test_lockup_init()
Date:   Thu, 20 Aug 2020 11:20:56 +0200
Message-Id: <20200820091622.740690835@linuxfoundation.org>
In-Reply-To: <20200820091612.692383444@linuxfoundation.org>
References: <20200820091612.692383444@linuxfoundation.org>
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From: Tiezhu Yang <yangtiezhu@loongson.cn>

[ Upstream commit 3adf3bae0d612357da516d39e1584f1547eb6e86 ]

Since filp_open() returns an error pointer, we should use IS_ERR() to
check the return value and then return PTR_ERR() if failed to get the
actual return value instead of always -EINVAL.

E.g. without this patch:

[root@localhost loongson]# ls no_such_file
ls: cannot access no_such_file: No such file or directory
[root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S
modprobe: ERROR: could not insert 'test_lockup': Invalid argument
[root@localhost loongson]# dmesg | tail -1
[  126.100596] test_lockup: cannot find file_path

With this patch:

[root@localhost loongson]# ls no_such_file
ls: cannot access no_such_file: No such file or directory
[root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S
modprobe: ERROR: could not insert 'test_lockup': Unknown symbol in module, or unknown parameter (see dmesg)
[root@localhost loongson]# dmesg | tail -1
[   95.134362] test_lockup: failed to open no_such_file: -2

Fixes: aecd42df6d39 ("lib/test_lockup.c: add parameters for locking generic vfs locks")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/1595555407-29875-2-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 lib/test_lockup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/test_lockup.c b/lib/test_lockup.c
index bd7c7ff39f6be..e7202763a1688 100644
--- a/lib/test_lockup.c
+++ b/lib/test_lockup.c
@@ -512,8 +512,8 @@ static int __init test_lockup_init(void)
 	if (test_file_path[0]) {
 		test_file = filp_open(test_file_path, O_RDONLY, 0);
 		if (IS_ERR(test_file)) {
-			pr_err("cannot find file_path\n");
-			return -EINVAL;
+			pr_err("failed to open %s: %ld\n", test_file_path, PTR_ERR(test_file));
+			return PTR_ERR(test_file);
 		}
 		test_inode = file_inode(test_file);
 	} else if (test_lock_inode ||
-- 
2.25.1