On Thu, Feb 23, 2023 at 01:22:54PM +0000, Matthew Wilcox wrote: > But I'm suspicious of static match tools claiming it can't ever happen, > and I'd like more details please. I can't find the original report. I would never write a warning like that... However at the time when I reported the bug then Smatch did say that all the callers passed a non-NULL file pointer. I've reviewed my logs and that was true when I said it but it's not true now. :( Now Smatch says there are three callers and nfs_write_begin() passes a valid pointer, read_pages() passes either a valid pointer or a NULL and filemap_read_folio() passes an unknown pointer. https://lore.kernel.org/all/Y77+n9MyHgx%2FalA4@kadam/ The issue here is that the pointer was already derefernced on the lines before the check for NULL. struct inode *inode = file_inode(file); So either the dereference or the check was wrong. regards, dan carpenter
