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Code Issues Releases Wiki Activity

jump_label: Fix jump_label_text_reserved() vs __init 

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 e7bf1ba97a ("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: 4c3ef6d793 ("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
This commit is contained in:
Peter Zijlstra 2021-06-28 13:24:10 +02:00 committed by Ingo Molnar
parent 4840ce2267
commit 9e667624c2
1 changed files with 8 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
kernel/jump_label.c
View File

@ -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++;
}
@ -562,7 +564,7 @@ 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);
@ -788,8 +790,9 @@ 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;