On Mon, 16 Apr 2018, Petr Mladek wrote: > Nikolai started to use shadow variables and found that list_head > is not initialized correctly using the existing API. > > The problem is that LIST_HEAD_INIT() set pointers to itself. > klp_shadow_alloc() then copies these pointers to another location. > > It would be possible to solve this by a late initialization. But > this does not work well with klp_shadow_get_or_alloc(). Also this > behavior is error prone. Note that list_head might be hidden in > another structure, for example mutex. > > I suggest to change the API and allow to initialize the shadow > variables using a custom callback. I think that we have already > talked about this but we decided to go the easier way. It seems > that it was a bad decision. > > I send also patch that add a symmetric callback to the klp_shadow_free() > functions. It might be handy especially for klp_shadow_free_all(). > > > Changes against v2: > > + Use pr_err() instead of WARN() when ctor() fails [Josh] > + Some typos [Mirek] > > > Changes against v1: > > + Rename init/free callbacks to ctor/dtor > + Misc update of comments and commit messages > + Fix sizeof() in the sample code in shadow-vars.txt > > > Petr Mladek (2): > livepatch: Initialize shadow variables safely by a custom callback > livepatch: Allow to call a custom callback when freeing shadow > variables > > Documentation/livepatch/shadow-vars.txt | 41 ++++++++---- > include/linux/livepatch.h | 19 ++++-- > kernel/livepatch/shadow.c | 108 > ++++++++++++++++++++---------- > samples/livepatch/livepatch-shadow-fix1.c | 43 +++++++++--- > samples/livepatch/livepatch-shadow-fix2.c | 33 ++++----- > 5 files changed, 163 insertions(+), 81 deletions(-)
Acked-by: Miroslav Benes <[email protected]> M
