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authorMasami Hiramatsu <mhiramat@kernel.org>2020-08-29 22:02:47 +0900
committerIngo Molnar <mingo@kernel.org>2020-09-08 11:52:35 +0200
commitb338817807538c893540e393856b79cbbdf777ea (patch)
treebf4dadbf3fc3746a7028c415f2baf40032c95e99 /kernel/kprobes.c
parente03b4a084ea6b0a18b0e874baec439e69090c168 (diff)
kprobes: Free kretprobe_instance with RCU callback
Free kretprobe_instance with RCU callback instead of directly freeing the object in the kretprobe handler context. This will make kretprobe run safer in NMI context. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/159870616685.1229682.11978742048709542226.stgit@devnote2
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r--kernel/kprobes.c25
1 files changed, 6 insertions, 19 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 211138225fa5..0676868f1ac2 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1223,8 +1223,7 @@ void kprobes_inc_nmissed_count(struct kprobe *p)
}
NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
-void recycle_rp_inst(struct kretprobe_instance *ri,
- struct hlist_head *head)
+static void recycle_rp_inst(struct kretprobe_instance *ri)
{
struct kretprobe *rp = ri->rp;
@@ -1236,8 +1235,7 @@ void recycle_rp_inst(struct kretprobe_instance *ri,
hlist_add_head(&ri->hlist, &rp->free_instances);
raw_spin_unlock(&rp->lock);
} else
- /* Unregistering */
- hlist_add_head(&ri->hlist, head);
+ kfree_rcu(ri, rcu);
}
NOKPROBE_SYMBOL(recycle_rp_inst);
@@ -1313,7 +1311,7 @@ void kprobe_busy_end(void)
void kprobe_flush_task(struct task_struct *tk)
{
struct kretprobe_instance *ri;
- struct hlist_head *head, empty_rp;
+ struct hlist_head *head;
struct hlist_node *tmp;
unsigned long hash, flags = 0;
@@ -1323,19 +1321,14 @@ void kprobe_flush_task(struct task_struct *tk)
kprobe_busy_begin();
- INIT_HLIST_HEAD(&empty_rp);
hash = hash_ptr(tk, KPROBE_HASH_BITS);
head = &kretprobe_inst_table[hash];
kretprobe_table_lock(hash, &flags);
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task == tk)
- recycle_rp_inst(ri, &empty_rp);
+ recycle_rp_inst(ri);
}
kretprobe_table_unlock(hash, &flags);
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
kprobe_busy_end();
}
@@ -1936,13 +1929,12 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
void *frame_pointer)
{
struct kretprobe_instance *ri = NULL, *last = NULL;
- struct hlist_head *head, empty_rp;
+ struct hlist_head *head;
struct hlist_node *tmp;
unsigned long flags;
kprobe_opcode_t *correct_ret_addr = NULL;
bool skipped = false;
- INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags);
/*
@@ -2011,7 +2003,7 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
__this_cpu_write(current_kprobe, prev);
}
- recycle_rp_inst(ri, &empty_rp);
+ recycle_rp_inst(ri);
if (ri == last)
break;
@@ -2019,11 +2011,6 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
kretprobe_hash_unlock(current, &flags);
- hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
- hlist_del(&ri->hlist);
- kfree(ri);
- }
-
return (unsigned long)correct_ret_addr;
}
NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)