From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 9e667624c291753b8a5128f620f493d0b5226063 ]
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 Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Masami Hiramatsu mhiramat@kernel.org Link: https://lore.kernel.org/r/20210628113045.045141693@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/jump_label.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index a0c325664190..4ae693ce71a4 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -316,14 +316,16 @@ static int addr_conflict(struct jump_entry *entry, void *start, void *end) }
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_reserved(void *start, void *end)
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;