Description

In the Linux kernel, the following vulnerability has been resolved:

bpf: track changes_pkt_data property for global functions

When processing calls to certain helpers, verifier invalidates all
packet pointers in a current state. For example, consider the
following program:

__attribute__((__noinline__))
long skb_pull_data(struct __sk_buff *sk, __u32 len)
{
return bpf_skb_pull_data(sk, len);
}

SEC("tc")
int test_invalidate_checks(struct __sk_buff *sk)
{
int *p = (void *)(long)sk->data;
if ((void *)(p + 1) > (void *)(long)sk->data_end) return TCX_DROP;
skb_pull_data(sk, 0);
*p = 42;
return TCX_PASS;
}

After a call to bpf_skb_pull_data() the pointer 'p' can't be used
safely. See function filter.c:bpf_helper_changes_pkt_data() for a list
of such helpers.

At the moment verifier invalidates packet pointers when processing
helper function calls, and does not traverse global sub-programs when
processing calls to global sub-programs. This means that calls to
helpers done from global sub-programs do not invalidate pointers in
the caller state. E.g. the program above is unsafe, but is not
rejected by verifier.

This commit fixes the omission by computing field
bpf_subprog_info->changes_pkt_data for each sub-program before main
verification pass.
changes_pkt_data should be set if:
- subprogram calls helper for which bpf_helper_changes_pkt_data
returns true;
- subprogram calls a global function,
fo...

Classification

CVE ID: CVE-2024-58098

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 4.36% (scored less or equal to compared to others)

EPSS Date: 2025-06-03 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2024-58098
https://git.kernel.org/stable/c/1d572c60488b52882b719ed273767ee3b280413d
https://git.kernel.org/stable/c/51081a3f25c742da5a659d7fc6fd77ebfdd555be

Timeline