[SRU][M][PATCH 0/1] CVE-2024-26591

Bethany Jamison bethany.jamison at canonical.com
Fri Mar 8 21:15:36 UTC 2024


[Impact]

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:
     <TASK>
     ? __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.

[Fix]

Mantic: Clean cherry-pick.

[Test Case]

Compile and boot tested.

[Where problems could occur]

Issues could occur when the user uses bpf, though the risk of regression
is reasonably low as the only change is an additional validation check.

Jiri Olsa (1):
  bpf: Fix re-attachment branch in bpf_tracing_prog_attach

 kernel/bpf/syscall.c | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.34.1




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