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With KUAP enabled, any kernel code which wants to access userspace needs to be surrounded by disable-enable KUAP. But that is not happening for BPF_PROBE_MEM load instruction. Though PPC32 does not support read protection, considering the fact that PTR_TO_BTF_ID (which uses BPF_PROBE_MEM mode) could either be a valid kernel pointer or NULL but should never be a pointer to userspace address, execute BPF_PROBE_MEM load only if addr is kernel address, otherwise set dst_reg=0 and move on. This will catch NULL, valid or invalid userspace pointers. Only bad kernel pointer will be handled by BPF exception table. [Alexei suggested for x86] Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211012123056.485795-9-hbathini@linux.ibm.com |
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| .. | ||
| bpf_jit64.h | ||
| bpf_jit_comp32.c | ||
| bpf_jit_comp64.c | ||
| bpf_jit_comp.c | ||
| bpf_jit.h | ||
| Makefile | ||