[PATCH v2 1/2] x86/kprobes: Fix __recover_optprobed_insn check optimizing logic

From: Yang Jihong
Date: Wed Feb 15 2023 - 22:45:09 EST


Since the following commit:

commit f66c0447cca1 ("kprobes: Set unoptimized flag after unoptimizing code")

modified the update timing of the KPROBE_FLAG_OPTIMIZED, a optimized_kprobe
may be in the optimizing or unoptimizing state when op.kp->flags
has KPROBE_FLAG_OPTIMIZED and op->list is not empty.

The __recover_optprobed_insn check logic is incorrect, a kprobe in the
unoptimizing state may be incorrectly determined as unoptimizing.
As a result, incorrect instructions are copied.

The optprobe_queued_unopt function needs to be exported for invoking in
arch directory.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: f66c0447cca1 ("kprobes: Set unoptimized flag after unoptimizing code")
Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx>
---
arch/x86/kernel/kprobes/opt.c | 4 ++--
include/linux/kprobes.h | 1 +
kernel/kprobes.c | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index e57e07b0edb6..f406bfa9a8cd 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -46,8 +46,8 @@ unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
/* This function only handles jump-optimized kprobe */
if (kp && kprobe_optimized(kp)) {
op = container_of(kp, struct optimized_kprobe, kp);
- /* If op->list is not empty, op is under optimizing */
- if (list_empty(&op->list))
+ /* If op is optimized or under unoptimizing */
+ if (list_empty(&op->list) || optprobe_queued_unopt(op))
goto found;
}
}
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index a0b92be98984..ab39285f71a6 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -378,6 +378,7 @@ extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
DEFINE_INSN_CACHE_OPS(optinsn);

extern void wait_for_kprobe_optimizer(void);
+bool optprobe_queued_unopt(struct optimized_kprobe *op);
#else /* !CONFIG_OPTPROBES */
static inline void wait_for_kprobe_optimizer(void) { }
#endif /* CONFIG_OPTPROBES */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1c18ecf9f98b..90b0fac6efa0 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -662,7 +662,7 @@ void wait_for_kprobe_optimizer(void)
mutex_unlock(&kprobe_mutex);
}

-static bool optprobe_queued_unopt(struct optimized_kprobe *op)
+bool optprobe_queued_unopt(struct optimized_kprobe *op)
{
struct optimized_kprobe *_op;

--
2.30.GIT