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authorYoulin Li <liulin063@gmail.com>2022-11-03 12:34:39 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2022-11-04 02:24:12 +0300
commitf1db20814af532f85e091231223e5e4818e8464b (patch)
treefd056852b9da624c5355d39a81032e9410053c36 /kernel
parent8bbabb3fddcd0f858be69ed5abc9b470a239d6f2 (diff)
downloadlinux-f1db20814af532f85e091231223e5e4818e8464b.tar.xz
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')
-rw-r--r--kernel/bpf/verifier.c8
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;