First user of skb_poison_list is in kfree_skb_list_reason, to catch bugs
earlier like introduced in commit
eedade12f4cb ("net: kfree_skb_list use
kmem_cache_free_bulk"). For completeness mentioned bug have been fixed in
commit
f72ff8b81ebc ("net: fix kfree_skb_list use of skb_mark_not_on_list").
In case of a bug like mentioned commit we would have seen OOPS with:
general protection fault, probably for non-canonical address 0xdead000000000870
And content of one the registers e.g. R13:
dead000000000800
In this case skb->len is at offset 112 bytes (0x70) why fault happens at
0x800+0x70 = 0x870
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
/********** net/core/page_pool.c **********/
#define PP_SIGNATURE (0x40 + POISON_POINTER_DELTA)
/********** net/core/page_pool.c **********/
#define PP_SIGNATURE (0x40 + POISON_POINTER_DELTA)
+/********** net/core/skbuff.c **********/
+#define SKB_LIST_POISON_NEXT ((void *)(0x800 + POISON_POINTER_DELTA))
+
/********** kernel/bpf/ **********/
#define BPF_PTR_POISON ((void *)(0xeB9FUL + POISON_POINTER_DELTA))
/********** kernel/bpf/ **********/
#define BPF_PTR_POISON ((void *)(0xeB9FUL + POISON_POINTER_DELTA))
+static inline void skb_poison_list(struct sk_buff *skb)
+{
+#ifdef CONFIG_DEBUG_NET
+ skb->next = SKB_LIST_POISON_NEXT;
+#endif
+}
+
/* Iterate through singly-linked GSO fragments of an skb. */
#define skb_list_walk_safe(first, skb, next_skb) \
for ((skb) = (first), (next_skb) = (skb) ? (skb)->next : NULL; (skb); \
/* Iterate through singly-linked GSO fragments of an skb. */
#define skb_list_walk_safe(first, skb, next_skb) \
for ((skb) = (first), (next_skb) = (skb) ? (skb)->next : NULL; (skb); \
while (segs) {
struct sk_buff *next = segs->next;
while (segs) {
struct sk_buff *next = segs->next;
- if (__kfree_skb_reason(segs, reason))
+ if (__kfree_skb_reason(segs, reason)) {
+ skb_poison_list(segs);
kfree_skb_add_bulk(segs, &sa, reason);
kfree_skb_add_bulk(segs, &sa, reason);