[PATCH bpf] bpf: fix bpf_dynptr_slice() returning ERR_PTR() on erro

[Andrii Nakryiko <andrii@kernel.org>]

Let's fix it for real this time. It shouldn't just detect ERR_PTR()
return from bpf_xdp_pointer(), but also turn that into NULL to follow
bpf_dynptr_slice() contract.

Fixes: 5426700e6841 ("bpf: fix bpf_dynptr_slice() to stop return an ERR_PTR.")
Fixes: 66e3a13e7c2c ("bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 kernel/bpf/helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 56b0c1f678ee..04049097176c 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2309,7 +2309,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
 	{
 		void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset + offset, len);
 		if (!IS_ERR_OR_NULL(xdp_ptr))
-			return xdp_ptr;
+			return NULL;
 
 		if (!buffer__opt)
 			return NULL;
-- 
2.34.1