NuytsTech Security

CVE-2024-26591

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In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix re-attachment branch in bpf_tracing_prog_attach

The following case can cause a crash due to missing attach_btf:

1) load rawtp program
2) load fentry program with rawtp as target_fd
3) create tracing link for fentry program with target_fd = 0
4) repeat 3

In the end we have:

– prog->aux->dst_trampoline == NULL
– tgt_prog == NULL (because we did not provide target_fd to link_create)
– prog->aux->attach_btf == NULL (the program was loaded with attach_prog_fd=X)
– the program was loaded for tgt_prog but we have no way to find out which one

BUG: kernel NULL pointer dereference, address: 0000000000000058
Call Trace:

? __die+0x20/0x70
? page_fault_oops+0x15b/0x430
? fixup_exception+0x22/0x330
? exc_page_fault+0x6f/0x170
? asm_exc_page_fault+0x22/0x30
? bpf_tracing_prog_attach+0x279/0x560
? btf_obj_id+0x5/0x10
bpf_tracing_prog_attach+0x439/0x560
__sys_bpf+0x1cf4/0x2de0
__x64_sys_bpf+0x1c/0x30
do_syscall_64+0x41/0xf0
entry_SYSCALL_64_after_hwframe+0x6e/0x76

Return -EINVAL in this situation.

More information : https://git.kernel.org/stable/c/50ae82f080cf87e84828f066c31723b781d68f5b

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