Commit 11ae737e authored by Amery Hung's avatar Amery Hung Committed by Jakub Kicinski
Browse files

selftests: drv-net: Reload pkt pointer after calling filter_udphdr 



Fix a verification failure. filter_udphdr() calls bpf_xdp_pull_data(),
which will invalidate all pkt pointers. Therefore, all ctx->data loaded
before filter_udphdr() cannot be used. Reload it to prevent verification
errors.

The error may not appear on some compiler versions if they decide to
load ctx->data after filter_udphdr() when it is first used.

Fixes: efec2e55 ("selftests: drv-net: Pull data before parsing headers")
Signed-off-by: default avatarAmery Hung <ameryhung@gmail.com>
Acked-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250925161452.1290694-1-ameryhung@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent dd5629a6

tools/testing/selftests/net/lib/xdp_native.bpf.c

+4 −5
Original line number Diff line number Diff line
@@ -420,7 +420,6 @@ static int xdp_adjst_tail_grow_data(struct xdp_md *ctx, __u16 offset) 


static int xdp_adjst_tail(struct xdp_md *ctx, __u16 port)

{

	void *data = (void *)(long)ctx->data;

	struct udphdr *udph = NULL;

	__s32 *adjust_offset, *val;

	__u32 key, hdr_len;
@@ -432,7 +431,8 @@ static int xdp_adjst_tail(struct xdp_md *ctx, __u16 port) 
	if (!udph)

		return XDP_PASS;



	hdr_len = (void *)udph - data + sizeof(struct udphdr);

	hdr_len = (void *)udph - (void *)(long)ctx->data +

		  sizeof(struct udphdr);

	key = XDP_ADJST_OFFSET;

	adjust_offset = bpf_map_lookup_elem(&map_xdp_setup, &key);

	if (!adjust_offset)
@@ -572,8 +572,6 @@ static int xdp_adjst_head_grow_data(struct xdp_md *ctx, __u64 hdr_len, 


static int xdp_head_adjst(struct xdp_md *ctx, __u16 port)

{

	void *data_end = (void *)(long)ctx->data_end;

	void *data = (void *)(long)ctx->data;

	struct udphdr *udph_ptr = NULL;

	__u32 key, size, hdr_len;

	__s32 *val;
@@ -584,7 +582,8 @@ static int xdp_head_adjst(struct xdp_md *ctx, __u16 port) 
	if (!udph_ptr)

		return XDP_PASS;



	hdr_len = (void *)udph_ptr - data + sizeof(struct udphdr);

	hdr_len = (void *)udph_ptr - (void *)(long)ctx->data +

		  sizeof(struct udphdr);



	key = XDP_ADJST_OFFSET;

	val = bpf_map_lookup_elem(&map_xdp_setup, &key);