module: propagate error in modules_open()

clyu · Jessica Yu · commit 3f553b308bb0 · 2018-03-08T21:58:51.000+01:00
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: 516fb7f ("/proc/module: use the same logic as /proc/kallsyms for address exposure") Cc: Jessica Yu <jeyu@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@vger.kernel.org # 4.15+ Signed-off-by: Leon Yu <chianglungyu@gmail.com> Signed-off-by: Jessica Yu <jeyu@kernel.org>
diff --git 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 = {

Original file line number	Diff line number	Diff line change
`@@ -4228,7 +4228,7 @@ static int modules_open(struct inode inode, struct file file)`
`4228`	`4228`	`m->private = kallsyms_show_value() ? NULL : (void *)8ul;`
`4229`	`4229`	`}`
`4230`	`4230`
`4231`		`- return 0;`
	`4231`	`+ return err;`
`4232`	`4232`	`}`
`4233`	`4233`
`4234`	`4234`	`static const struct file_operations proc_modules_operations = {`