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>
diff --git a/sound/core/info.c b/sound/core/info.c
index 291d6ed..8ab72e0 100644
--- a/sound/core/info.c
+++ b/sound/core/info.c
@@ -325,6 +325,8 @@
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 @@
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);
}