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jump_label: Fix jump_label_text_reserved() vs __init

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[ 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: 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
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Peter Zijlstra
2021-06-28 13:24:10 +02:00
committed by Greg Kroah-Hartman
parent 143a6b8ec5
commit 59ae35884c
1 changed files with 8 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
kernel/jump_label.c
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@@ -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, 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; struct jump_entry *iter;
iter = iter_start; iter = iter_start;
while (iter < iter_stop) { while (iter < iter_stop) {
if (init || !jump_entry_is_init(iter)) {
if (addr_conflict(iter, start, end)) if (addr_conflict(iter, start, end))
return 1; return 1;
}
iter++; iter++;
} }
@@ -561,7 +563,7 @@ static int __jump_label_mod_text_reserved(void *start, void *end)
ret = __jump_label_text_reserved(mod->jump_entries, ret = __jump_label_text_reserved(mod->jump_entries,
mod->jump_entries + mod->num_jump_entries, mod->jump_entries + mod->num_jump_entries,
start, end); start, end, mod->state == MODULE_STATE_COMING);
module_put(mod); module_put(mod);
@@ -786,8 +788,9 @@ early_initcall(jump_label_init_module);
*/ */
int jump_label_text_reserved(void *start, void *end) int jump_label_text_reserved(void *start, void *end)
{ {
bool init = system_state < SYSTEM_RUNNING;
int ret = __jump_label_text_reserved(__start___jump_table, int ret = __jump_label_text_reserved(__start___jump_table,
__stop___jump_table, start, end); __stop___jump_table, start, end, init);
if (ret) if (ret)
return ret; return ret;