[PATCH] kprobes: fix out-of-bounds in register_kretprobe

[zhangyue]

When the data 'rp->data_size' is negative, the code
'sizeof(struct kretprobe_instance)+rp->data_size'
is less than 'sizeof(struct kretprobe_instance)'

At this time, the pointer 'inst' may be out of
bound when it is in use.

Signed-off-by: zhangyue <zhangyue1@xxxxxxxxxx>
---
 kernel/kprobes.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1cf8bca1ea86..71cf6bde299f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1983,7 +1983,7 @@ int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long o
 int register_kretprobe(struct kretprobe *rp)
 {
 	int ret;
-	struct kretprobe_instance *inst;
+	struct kretprobe_instance *inst = NULL;
 	int i;
 	void *addr;
 
@@ -2024,7 +2024,8 @@ int register_kretprobe(struct kretprobe *rp)
 
 	rp->rph->rp = rp;
 	for (i = 0; i < rp->maxactive; i++) {
-		inst = kzalloc(sizeof(struct kretprobe_instance) +
+		if (rp->data_size >= 0)
+			inst = kzalloc(sizeof(struct kretprobe_instance) +
 			       rp->data_size, GFP_KERNEL);
 		if (inst == NULL) {
 			refcount_set(&rp->rph->ref, i);
-- 
2.30.0