| Message ID | 20221103093440.3161-1-liulin063@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f1db20814af532f85e091231223e5e4818e8464b |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf,1/2,v2] bpf: Fix wrong reg type conversion in release_reference() | expand |
Hello: This series was applied to bpf/bpf.git (master) by Daniel Borkmann <daniel@iogearbox.net>: On Thu, 3 Nov 2022 17:34:39 +0800 you wrote: > Some helper functions will allocate memory. To avoid memory leaks, the > verifier requires the eBPF program to release these memories by calling > the corresponding helper functions. > > When a resource is released, all pointer registers corresponding to the > resource should be invalidated. The verifier use release_references() to > do this job, by apply __mark_reg_unknown() to each relevant register. > > [...] Here is the summary with links: - [bpf,1/2,v2] bpf: Fix wrong reg type conversion in release_reference() https://git.kernel.org/bpf/bpf/c/f1db20814af5 - [bpf,2/2] selftests/bpf: Add verifier test for release_reference() https://git.kernel.org/bpf/bpf/c/475244f5e06b You are awesome, thank you!
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9ab7188d8f68..1bb797bf9bbc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6618,8 +6618,12 @@ static int release_reference(struct bpf_verifier_env *env, return err; bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ - if (reg->ref_obj_id == ref_obj_id) - __mark_reg_unknown(env, reg); + if (reg->ref_obj_id == ref_obj_id) { + if (!env->allow_ptr_leaks) + __mark_reg_not_init(env, reg); + else + __mark_reg_unknown(env, reg); + } })); return 0;
Some helper functions will allocate memory. To avoid memory leaks, the verifier requires the eBPF program to release these memories by calling the corresponding helper functions. When a resource is released, all pointer registers corresponding to the resource should be invalidated. The verifier use release_references() to do this job, by apply __mark_reg_unknown() to each relevant register. It will give these registers the type of SCALAR_VALUE. A register that will contain a pointer value at runtime, but of type SCALAR_VALUE, which may allow the unprivileged user to get a kernel pointer by storing this register into a map. Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this problem. Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") Signed-off-by: Youlin Li <liulin063@gmail.com> --- v1->v2: Use __mark_reg_not_init() only when !allow_ptr_leaks. kernel/bpf/verifier.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)