Enforce XDP_FLAGS_UPDATE_IF_NOEXIST only if new BPF program to be attached is
non-NULL (i.e., we are not detaching a BPF program).
Reported-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
Fixes: d4baa9368a5e ("bpf, xdp: Extract common XDP program attachment logic")
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
net/core/dev.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 7df6c9617321..b5d1129d8310 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8913,10 +8913,6 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
NL_SET_ERR_MSG(extack, "Active program does not match expected");
return -EEXIST;
}
- if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
- NL_SET_ERR_MSG(extack, "XDP program already attached");
- return -EBUSY;
- }
/* put effective new program into new_prog */
if (link)
@@ -8927,6 +8923,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
? XDP_MODE_DRV : XDP_MODE_SKB;
+ if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
+ NL_SET_ERR_MSG(extack, "XDP program already attached");
+ return -EBUSY;
+ }
if (!offload && dev_xdp_prog(dev, other_mode)) {
NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
return -EEXIST;
--
2.24.1
