From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
[ 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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210628113045.045141693@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 ba39fbb1f8e7..af520ca26360 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;
--
2.30.2
