On 8/7/23 10:07 AM, Kui-Feng Lee wrote:
On 8/4/23 15:26, Martin KaFai Lau wrote:
On 8/3/23 4:12 PM, thinker.li@xxxxxxxxx wrote:
From: Kui-Feng Lee <thinker.li@xxxxxxxxx>
Verify if the pointer obtained from bpf_xdp_pointer() is either an error or
NULL before returning it.
The function bpf_dynptr_slice() mistakenly returned an ERR_PTR. Instead of
solely checking for NULL, it should also verify if the pointer returned by
bpf_xdp_pointer() is an error or NULL.
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes:
https://lore.kernel.org/bpf/d1360219-85c3-4a03-9449-253ea905f9d1@moroto.mountain/
Fixes: 66e3a13e7c2c ("bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr")
Suggested-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>
---
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 56ce5008aedd..eb91cae0612a 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2270,7 +2270,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct
bpf_dynptr_kern *ptr, u32 offset
case BPF_DYNPTR_TYPE_XDP:
{
void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset + offset, len);
- if (xdp_ptr)
+ if (!IS_ERR_OR_NULL(xdp_ptr))
Considering the earlier bpf_dynptr_check_off_len() should have avoided the
IS_ERR() case here, I think targeting bpf-next makes sense. Applied.
It is a good point. I think the bpf_dynptr_check_off_len() check is
wrong as well. According to the behavior of the rest of the function,
it should be
err = bpf_dynptr_check_off_len(ptr, ptr->offset + offset, len);
Not sure why it is needed either.
The bpf_dynptr_adjust() has updated the size after updating the offset.
Did I missing other offset update places?
