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Subject[RFC PATCH tip/master 3/3] kprobes: Limit kretprobe maximum instances
Date
Limit kretprobe maximum instance up to MAXACTIVE_ALLOC.
Without this limit, kretprobe user can specify huge number
(e.g. forget to zero-fill struct kretprobe) to maxactive
and may cause out-of-memory.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/kprobes.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 75c5390..f1bebcf 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1942,6 +1942,9 @@ int register_kretprobe(struct kretprobe *rp)
rp->kp.break_handler = NULL;

/* Pre-allocate memory for max kretprobe instances */
+ if (rp->maxactive > KRETPROBE_MAXACTIVE_ALLOC)
+ return -E2BIG;
+
if (rp->maxactive <= 0) {
#ifdef CONFIG_PREEMPT
rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
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