From: Daniel Borkmann <daniel@iogearbox.net> mainline inclusion from mainline-v6.17-rc1 commit abad3d0bad72a52137e0c350c59542d75ae4f513 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICTB0G CVE: CVE-2025-38502 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Lonial reported that an out-of-bounds access in cgroup local storage can be crafted via tail calls. Given two programs each utilizing a cgroup local storage with a different value size, and one program doing a tail call into the other. The verifier will validate each of the indivial programs just fine. However, in the runtime context the bpf_cg_run_ctx holds an bpf_prog_array_item which contains the BPF program as well as any cgroup local storage flavor the program uses. Helpers such as bpf_get_local_storage() pick this up from the runtime context: ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx); storage = ctx->prog_item->cgroup_storage[stype]; if (stype == BPF_CGROUP_STORAGE_SHARED) ptr = &READ_ONCE(storage->buf)->data[0]; else ptr = this_cpu_ptr(storage->percpu_buf); For the second program which was called from the originally attached one, this means bpf_get_local_storage() will pick up the former program's map, not its own. With mismatching sizes, this can result in an unintended out-of-bounds access. To fix this issue, we need to extend bpf_map_owner with an array of storage_cookie[] to match on i) the exact maps from the original program if the second program was using bpf_get_local_storage(), or ii) allow the tail call combination if the second program was not using any of the cgroup local storage maps. Fixes: 7d9c3427894f ("bpf: Make cgroup storages shared between programs on the same cgroup") Reported-by: Lonial Con <kongln9170@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20250730234733.530041-4-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov <ast@kernel.org> Conflicts: include/linux/bpf.h [The conflicts were due to some minor issue.] Signed-off-by: Xiaomeng Zhang <zhangxiaomeng13@huawei.com> --- include/linux/bpf.h | 1 + kernel/bpf/core.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ff155f7fe922..c524abdbd1ca 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -273,6 +273,7 @@ struct bpf_map_owner { enum bpf_prog_type type; bool jited; bool xdp_has_frags; + u64 storage_cookie[MAX_BPF_CGROUP_STORAGE_TYPE]; const struct btf_type *attach_func_proto; }; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 7d87933d0e46..b190fbb96256 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2264,7 +2264,9 @@ bool bpf_prog_map_compatible(struct bpf_map *map, { enum bpf_prog_type prog_type = resolve_prog_type(fp); struct bpf_prog_aux *aux = fp->aux; + enum bpf_cgroup_storage_type i; bool ret = false; + u64 cookie; if (fp->kprobe_override) return ret; @@ -2287,11 +2289,24 @@ bool bpf_prog_map_compatible(struct bpf_map *map, map->owner->jited = fp->jited; map->owner->xdp_has_frags = aux->xdp_has_frags; map->owner->attach_func_proto = aux->attach_func_proto; + for_each_cgroup_storage_type(i) { + map->owner->storage_cookie[i] = + aux->cgroup_storage[i] ? + aux->cgroup_storage[i]->cookie : 0; + } ret = true; } else { ret = map->owner->type == prog_type && map->owner->jited == fp->jited && map->owner->xdp_has_frags == aux->xdp_has_frags; + for_each_cgroup_storage_type(i) { + if (!ret) + break; + cookie = aux->cgroup_storage[i] ? + aux->cgroup_storage[i]->cookie : 0; + ret = map->owner->storage_cookie[i] == cookie || + !cookie; + } if (ret && map->owner->attach_func_proto != aux->attach_func_proto) { switch (prog_type) { -- 2.34.1