linux-kernel - [PATCH resend] module: propagate error in modules

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Message-Id: <20180306151624.24196-1-chianglungyu@gmail.com>
Date:   Tue,  6 Mar 2018 23:16:24 +0800
From:   Leon Yu <chianglungyu@...il.com>
To:     Jessica Yu <jeyu@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Cc:     Leon Yu <chianglungyu@...il.com>, stable@...r.kernel.org
Subject: [PATCH resend] module: propagate error in modules_open()

otherwise kernel can oops later in seq_release() due to dereferencing null
file->private_data which is only set if seq_open() succeeds.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
IP: seq_release+0xc/0x30
Call Trace:
 close_pdeo+0x37/0xd0
 proc_reg_release+0x5d/0x60
 __fput+0x9d/0x1d0
 ____fput+0x9/0x10
 task_work_run+0x75/0x90
 do_exit+0x252/0xa00
 do_group_exit+0x36/0xb0
 SyS_exit_group+0xf/0x10

Fixes: 516fb7f2e73d ("/proc/module: use the same logic as /proc/kallsyms for address exposure")
Cc: Jessica Yu <jeyu@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: stable@...r.kernel.org # 4.15+
Signed-off-by: Leon Yu <chianglungyu@...il.com>
---
 kernel/module.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c
index ad2d420024f6..e42764acedb4 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4228,7 +4228,7 @@ static int modules_open(struct inode *inode, struct file *file)
 		m->private = kallsyms_show_value() ? NULL : (void *)8ul;
 	}
 
-	return 0;
+	return err;
 }
 
 static const struct file_operations proc_modules_operations = {
--
2.16.2