Commit 6809cd68 authored Oct 30, 2016 by Takashi Iwai

ALSA: info: Return error for invalid read/write



Currently the ALSA proc handler allows read or write even if the proc
file were write-only or read-only.  It's mostly harmless, does thing
but allocating memory and ignores the input/output.  But it doesn't
tell user about the invalid use, and it's confusing and inconsistent
in comparison with other proc files.

This patch adds some sanity checks and let the proc handler returning
an -EIO error when the invalid read/write is performed.

Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent 027a9fe6

sound/core/info.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -325,6 +325,8 @@ static ssize_t snd_info_text_entry_write(struct file *file,
		size_t next;
		int err = 0;

		if (!entry->c.text.write)
		return -EIO;
		pos = *offset;
		if (!valid_pos(pos, count))
		return -EIO;
		@@ -369,7 +371,9 @@ static int snd_info_seq_show(struct seq_file seq, void p)
		struct snd_info_private_data *data = seq->private;
		struct snd_info_entry *entry = data->entry;

		if (entry->c.text.read) {
		if (!entry->c.text.read) {
		return -EIO;
		} else {
		data->rbuffer->buffer = (char )seq; / XXX hack! */
		entry->c.text.read(entry, data->rbuffer);
		}

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