Public bug reported:

[ Impact ]

Previously applied patches to the generic kernel are making jammy:linux-
riscv-6.8 FTBFS because of missing declaration of some functions in
arch/riscv/net/bpf_jit.h.

Those previous patches were applied in bulk as part of upstream stable patchset 
2026-01-26.
See https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2139072

The following commit, fixing CVE-2025-40079, from kernel 6.12, uses functions 
that were not yet defined in 6.8:
 riscv, bpf: Sign extend struct ops return values properly 
(fd2e08128944a7679e753f920e9eda72057e427c)

Error log:
/build/jammy/arch/riscv/net/bpf_jit_comp64.c:582:17: error: implicit 
declaration of function 'emit_sextb'; did you mean 'emit_sub'? 
[-Werror=implicit-function-declaration]
/build/jammy/arch/riscv/net/bpf_jit_comp64.c:585:17: error: implicit 
declaration of function 'emit_sexth'; did you mean 'emit_zext_32'? 
[-Werror=implicit-function-declaration]
/build/jammy/arch/riscv/net/bpf_jit_comp64.c:588:17: error: implicit 
declaration of function 'emit_sextw'; did you mean 'emit_subw'? 
[-Werror=implicit-function-declaration]
... and more missing functions

[ Fix ]

Cherry picked 3 missing commits from upstream:
- e33758f7493c9ad8cf6960bcf7c70f5761f3acfb "riscv, bpf: Unify 32-bit 
sign-extension to emit_sextw"
- 5090b339eeb3417baa940d690923e630e077d8f8 "riscv, bpf: Add rv_ext_enabled 
macro for runtime detection extentsion"
- 647b93f65daa128d9a0e4aac744a5fcf5f58b2d2 "riscv, bpf: Add necessary Zbb 
instructions"

Those commits add definitions for the missing functions emit_sextX and
others.

[ Test Case ]

Kernel build succeeded.

** Affects: linux-riscv-6.8 (Ubuntu)
     Importance: Undecided
     Assignee: Sarah Emery (semerys)
         Status: In Progress

-- 
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2142235

Title:
  linux-riscv-6.8 is FTBFS because of missing patches

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux-riscv-6.8/+bug/2142235/+subscriptions


-- 
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs

Reply via email to