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From: Peter Zijlstra <peterz@infradead.org>
To: jpoimboe@redhat.com, jbaron@akamai.com, rostedt@goodmis.org,
	ardb@kernel.org, naveen.n.rao@linux.ibm.com,
	anil.s.keshavamurthy@intel.com, mhiramat@kernel.org,
	davem@davemloft.net
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	kernel test robot <oliver.sang@intel.com>
Subject: [PATCH 1/3] jump_label: Fix jump_label_text_reserved() vs __init
Date: Mon, 28 Jun 2021 13:24:10 +0200
Message-ID: <20210628113045.045141693@infradead.org> (raw)
In-Reply-To: <20210628112409.233121975@infradead.org>

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>
---
 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;



  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-28 11:24 [PATCH 0/3] jump_label/static_call/kprobes: *_text_reserved() fixes Peter Zijlstra
2021-06-28 11:24 ` Peter Zijlstra [this message]
2021-06-28 13:43   ` [PATCH 1/3] jump_label: Fix jump_label_text_reserved() vs __init Masami Hiramatsu
2021-07-05  7:53   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-07-05  9:05   ` tip-bot2 for Peter Zijlstra
2021-06-28 11:24 ` [PATCH 2/3] static_call: Fix static_call_text_reserved() " Peter Zijlstra
2021-06-28 14:26   ` Masami Hiramatsu
2021-07-05  7:53   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-07-05  9:05   ` tip-bot2 for Peter Zijlstra
2021-06-28 11:24 ` [PATCH 3/3] kprobe/static_call: Restore missing static_call_text_reserved() Peter Zijlstra
2021-06-28 11:34   ` Peter Zijlstra
2021-06-28 14:24     ` Masami Hiramatsu
2021-06-28 15:03       ` Peter Zijlstra
2021-06-28 14:25   ` Masami Hiramatsu
2021-07-05  7:53   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-07-05  9:05   ` tip-bot2 for Peter Zijlstra

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