accel/ivpu: prevent uninitialized data bug in debugfs

The simple_write_to_buffer() will only initialize data starting from
the *pos offset so if it's non-zero then the first part of the buffer
uninitialized.  Really, if *pos is non-zero then this code won't work
so just check for that at the start of the function.

Fixes: 320323d2e545 ("accel/ivpu: Add debugfs interface for setting HWS priority bands")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Link: https://patch.msgid.link/ahP24m6Mii9EDL7Q@stanley.mountain

diff --git a/drivers/accel/ivpu/ivpu_debugfs.c b/drivers/accel/ivpu/ivpu_debugfs.c
index 189dbe94cf14109974945a15d61bc96f4ec70fcc..dc20bc73c6ed8f535ffd266986ae01b3ae334522 100644 (file)
--- a/drivers/accel/ivpu/ivpu_debugfs.c
+++ b/drivers/accel/ivpu/ivpu_debugfs.c
@@ -450,7 +450,7 @@ priority_bands_fops_write(struct file *file, const char __user *user_buf, size_t
        u32 band;
        int ret;
 
-       if (size >= sizeof(buf))
+       if (*pos != 0 || size >= sizeof(buf))
                return -EINVAL;
 
        ret = simple_write_to_buffer(buf, sizeof(buf) - 1, pos, user_buf, size);