| Message ID | 20181001081324.11553-1-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | kernel: jump_label: fix NULL dereference bug in __jump_label_mod_update() | expand |
On Mon, Oct 1, 2018 at 1:13 AM, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > Commit 19483677684b ("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: 19483677684b ("jump_label: Annotate entries that operate on ...") > Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Jessica Yu <jeyu@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > --- > kernel/jump_label.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/jump_label.c b/kernel/jump_label.c > index e8cf3ff3149c..14a7f9881745 100644 > --- a/kernel/jump_label.c > +++ b/kernel/jump_label.c > @@ -516,7 +516,7 @@ static void __jump_label_mod_update(struct static_key *key) > else > stop = m->jump_entries + m->num_jump_entries; > __jump_label_update(key, mod->entries, stop, > - m->state == MODULE_STATE_COMING); > + m && m->state == MODULE_STATE_COMING); > } > } > > -- > 2.17.1 > -- Kees Cook Pixel Security
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index e8cf3ff3149c..14a7f9881745 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -516,7 +516,7 @@ static void __jump_label_mod_update(struct static_key *key) else stop = m->jump_entries + m->num_jump_entries; __jump_label_update(key, mod->entries, stop, - m->state == MODULE_STATE_COMING); + m && m->state == MODULE_STATE_COMING); } }
Commit 19483677684b ("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: 19483677684b ("jump_label: Annotate entries that operate on ...") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- kernel/jump_label.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.17.1