Commit 77ac1c02 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Thomas Gleixner

jump_label: Fix NULL dereference bug in __jump_label_mod_update()

Commit 19483677 ("jump_label: Annotate entries that operate on
__init code earlier") refactored the code that manages runtime
patching of jump labels in modules that are tied to static keys
defined in other modules or in the core kernel.

In the latter case, we may iterate over the static_key_mod linked
list until we hit the entry for the core kernel, whose 'mod' field
will be NULL, and attempt to dereference it to get at its 'state'
member.

So let's add a non-NULL check: this forces the 'init' argument of
__jump_label_update() to false for static keys that are defined in
the core kernel, which is appropriate given that __init annotated
jump_label entries in the core kernel should no longer be active
at this point (i.e., when loading modules).

Fixes: 19483677 ("jump_label: Annotate entries that operate on ...")
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20181001081324.11553-1-ard.biesheuvel@linaro.org
parent 57d15877
...@@ -516,7 +516,7 @@ static void __jump_label_mod_update(struct static_key *key) ...@@ -516,7 +516,7 @@ static void __jump_label_mod_update(struct static_key *key)
else else
stop = m->jump_entries + m->num_jump_entries; stop = m->jump_entries + m->num_jump_entries;
__jump_label_update(key, mod->entries, stop, __jump_label_update(key, mod->entries, stop,
m->state == MODULE_STATE_COMING); m && m->state == MODULE_STATE_COMING);
} }
} }
......
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