On Wed, Jun 03, 2020 at 07:47:14PM +0200, glider@xxxxxxxxxx wrote: > Under certain circumstances (we found this out running Docker on a > Clang-built kernel with CONFIG_INIT_STACK_ALL) ovl_copy_xattr() may > return uninitialized value of |error| from ovl_copy_xattr(). > It is then returned by ovl_create() to lookup_open(), which casts it to > an invalid dentry pointer, that can be further read or written by the > lookup_open() callers. > > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1050405 Fixes: e4ad29fa0d22 ("ovl: use a minimal buffer in ovl_copy_xattr") Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> It seems the error isn't reported anywhere, so the value likely isn't too important. -EINVAL seems sane to me. Thought: should CONFIG_INIT_STACK_ALL=y disable uninitialized_var()? $ git grep uninitialized_var | wc -l 300 We have evidence this is being used inappropriately and is masking bugs. I would actually think it should should be removed globally, but it seems especially important for CONFIG_INIT_STACK_ALL=y. I've opened: https://github.com/KSPP/linux/issues/81 -- Kees Cook
