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| author |   Masami Hiramatsu <mhiramat@kernel.org> | 2020-08-29 22:02:47 +0900 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2020-09-08 11:52:35 +0200 |
| commit | b338817807538c893540e393856b79cbbdf777ea (patch) | |
| tree | bf4dadbf3fc3746a7028c415f2baf40032c95e99 /kernel/kprobes.c | |
| parent | kprobes: Remove NMI context check (diff) | |
| download | linux-dev-b338817807538c893540e393856b79cbbdf777ea.tar.xz linux-dev-b338817807538c893540e393856b79cbbdf777ea.zip | |
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.c | 25 |
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) |