在 2021/4/22 下午11:16, Xuan Zhuo 写道:
When "headroom" > 0, the actual allocated memory space is the entire
page, so the address of the page should be used when passing it to
build_skb().
BUG: KASAN: use-after-free in skb_gro_receive (net/core/skbuff.c:4260)
Write of size 16 at addr ffff88811619fffc by task kworker/u9:0/534
CPU: 2 PID: 534 Comm: kworker/u9:0 Not tainted 5.12.0-rc7-custom-16372-gb150be05b806 #3382
Hardware name: QEMU MSN2700, BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Workqueue: xprtiod xs_stream_data_receive_workfn [sunrpc]
Call Trace:
<IRQ>
dump_stack (lib/dump_stack.c:122)
print_address_description.constprop.0 (mm/kasan/report.c:233)
kasan_report.cold (mm/kasan/report.c:400 mm/kasan/report.c:416)
skb_gro_receive (net/core/skbuff.c:4260)
tcp_gro_receive (net/ipv4/tcp_offload.c:266 (discriminator 1))
tcp4_gro_receive (net/ipv4/tcp_offload.c:316)
inet_gro_receive (net/ipv4/af_inet.c:1545 (discriminator 2))
dev_gro_receive (net/core/dev.c:6075)
napi_gro_receive (net/core/dev.c:6168 net/core/dev.c:6198)
receive_buf (drivers/net/virtio_net.c:1151) virtio_net
virtnet_poll (drivers/net/virtio_net.c:1415 drivers/net/virtio_net.c:1519) virtio_net
__napi_poll (net/core/dev.c:6964)
net_rx_action (net/core/dev.c:7033 net/core/dev.c:7118)
__do_softirq (./arch/x86/include/asm/jump_label.h:25 ./include/linux/jump_label.h:200 ./include/trace/events/irq.h:142 kernel/softirq.c:346)
irq_exit_rcu (kernel/softirq.c:221 kernel/softirq.c:422 kernel/softirq.c:434)
common_interrupt (arch/x86/kernel/irq.c:240 (discriminator 14))
</IRQ>
Fixes: fb32856b16ad ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
Tested-by: Ido Schimmel <idosch@xxxxxxxxxx>
---
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
The codes became hard to read, I think we can try to do some cleanups on
top to make it easier to read.
Thanks
drivers/net/virtio_net.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 74d2d49264f3..7fda2ae4c40f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -387,7 +387,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
unsigned int copy, hdr_len, hdr_padded_len;
struct page *page_to_free = NULL;
int tailroom, shinfo_size;
- char *p, *hdr_p;
+ char *p, *hdr_p, *buf;
p = page_address(page) + offset;
hdr_p = p;
@@ -403,11 +403,15 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
* space are aligned.
*/
if (headroom) {
- /* The actual allocated space size is PAGE_SIZE. */
+ /* Buffers with headroom use PAGE_SIZE as alloc size,
+ * see add_recvbuf_mergeable() + get_mergeable_buf_len()
+ */
truesize = PAGE_SIZE;
tailroom = truesize - len - offset;
+ buf = page_address(page);
} else {
tailroom = truesize - len;
+ buf = p;
}
len -= hdr_len;
@@ -416,11 +420,13 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+ /* copy small packet so we can reuse these pages */
if (!NET_IP_ALIGN && len > GOOD_COPY_LEN && tailroom >= shinfo_size) {
- skb = build_skb(p, truesize);
+ skb = build_skb(buf, truesize);
if (unlikely(!skb))
return NULL;
+ skb_reserve(skb, p - buf);
skb_put(skb, len);
goto ok;
}
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