Messages in this thread | | | Date | Mon, 28 Jun 2021 22:43:37 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 1/3] jump_label: Fix jump_label_text_reserved() vs __init |
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On Mon, 28 Jun 2021 13:24:10 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> It turns out that jump_label_text_reserved() was reporting __init text > as being reserved past the time when the __init text was freed and > re-used. > > For a long time, this resulted in, at worst, not being able to kprobe > text that happened to land at the re-used address. However a recent > commit e7bf1ba97afd ("jump_label, x86: Emit short JMP") made it a > fatal mistake because it now needs to read the instruction in order to > determine the conflict -- an instruction that's no longer there. > > Fixes: 4c3ef6d79328 ("jump label: Add jump_label_text_reserved() to reserve jump points") > Reported-by: kernel test robot <oliver.sang@intel.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Thank you,
> --- > kernel/jump_label.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > --- a/kernel/jump_label.c > +++ b/kernel/jump_label.c > @@ -316,14 +316,16 @@ static int addr_conflict(struct jump_ent > } > > static int __jump_label_text_reserved(struct jump_entry *iter_start, > - struct jump_entry *iter_stop, void *start, void *end) > + struct jump_entry *iter_stop, void *start, void *end, bool init) > { > struct jump_entry *iter; > > iter = iter_start; > while (iter < iter_stop) { > - if (addr_conflict(iter, start, end)) > - return 1; > + if (init || !jump_entry_is_init(iter)) { > + if (addr_conflict(iter, start, end)) > + return 1; > + } > iter++; > } > > @@ -561,7 +563,7 @@ static int __jump_label_mod_text_reserve > > ret = __jump_label_text_reserved(mod->jump_entries, > mod->jump_entries + mod->num_jump_entries, > - start, end); > + start, end, mod->state == MODULE_STATE_COMING); > > module_put(mod); > > @@ -786,8 +788,9 @@ early_initcall(jump_label_init_module); > */ > int jump_label_text_reserved(void *start, void *end) > { > + bool init = system_state < SYSTEM_RUNNING; > int ret = __jump_label_text_reserved(__start___jump_table, > - __stop___jump_table, start, end); > + __stop___jump_table, start, end, init); > > if (ret) > return ret; > >
-- Masami Hiramatsu <mhiramat@kernel.org>
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