On Wed, May 27, 2026 at 08:31:59PM -0400, Sean Anderson wrote: > On 5/25/26 03:16, Dan Carpenter wrote: > > If the *ppos is non-zero then simple_write_to_buffer() will not > > initialize the start of the buf[] buffer. It doesn't really make sense > > to allow non-zero values for *ppos, so check for that at the start and > > return -EINVAL. > > non-zero ppos seems to be handled properly by simple_write_to_buffer. >
It's not an overflow bug, it's an uninitialized variable bug. The simple_write_to_buffer() is designed to handle partial writes so it leaves the first "written" (scare quotes) part of the string as is. But in this case, we can't handle a partial write and the first part of buf[] is left uninitialized. https://staticthinking.wordpress.com/2026/05/23/simple_write_to_buffer-is-complicated/ Also this appears to be dead code since fops_zynqmp_dp_pattern is never used. regards, dan carpenter
