bpf: Fix a bpf_kptr_xchg() issue with local kptr #5549
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added 2 commits
August 20, 2023 17:09
When reviewing local percpu kptr support, Alexei discovered a bug wherea bpf_kptr_xchg() may succeed even if the map value kptr type and locally allocated obj type do not match ([1]). Missed struct btf_id comparison is the reason for the bug. This patch added such struct btf_id comparison and will flag verification failure if types do not match. [1] https://lore.kernel.org/bpf/20230819002907.io3iphmnuk43xblu@macbook-pro-8.dhcp.thefacebook.com/#t Reported-by: Alexei Starovoitov <ast@kernel.org> Fixes: 738c96d ("bpf: Allow local kptrs to be exchanged via bpf_kptr_xchg") Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
For a bpf_kptr_xchg() with local kptr, if the map value kptr type and allocated local obj type does not match, with the previous patch, the below verifier error message will be logged: R2 is of type <allocated local obj type> but <map value kptr type> is expected Without the previous patch, the test will have unexpected success. Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
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Upstream branch: 23d775f |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=777744 expired. Closing PR. |
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Pull request for series with
subject: bpf: Fix a bpf_kptr_xchg() issue with local kptr
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=777744