Re: [PATCH resend] module: propagate error in modules_open()

[Jessica Yu]

+++ Leon Yu [06/03/18 23:16 +0800]:
> 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@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 4.15+
> Signed-off-by: Leon Yu <chianglungyu@xxxxxxxxx>

Ah yeah, the error code was dropped in that commit. 

Applied, thanks for the fix.

Jessica

> ---
> 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