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| author | Youlin Li <liulin063@gmail.com> | 2022-11-03 17:34:39 +0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2022-11-04 00:24:12 +0100 |
| commit | f1db20814af532f85e091231223e5e4818e8464b (patch) | |
| tree | fd056852b9da624c5355d39a81032e9410053c36 /kernel/bpf | |
| parent | 8bbabb3fddcd0f858be69ed5abc9b470a239d6f2 (diff) | |
| download | linux-f1db20814af532f85e091231223e5e4818e8464b.tar.gz linux-f1db20814af532f85e091231223e5e4818e8464b.tar.bz2 linux-f1db20814af532f85e091231223e5e4818e8464b.zip | |
bpf: Fix wrong reg type conversion in release_reference()
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>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221103093440.3161-1-liulin063@gmail.com
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dd9019c8b0db..225666307bba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6623,8 +6623,12 @@ 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; |