bpf, riscv: Fix extable handling for arena load_acquire

Browse source

emit_atomic_ld_st() returns 1 to have build_body() skip the zext after
a sub-word load_acquire. The caller does "ret = ret ?:
add_exception_handler(...)", which skips add_exception_handler() on any
non-zero ret, so the extable entry is missing and a faulting
PROBE_ATOMIC load_acquire oopses.

REG_DONT_CLEAR_MARKER leaves rd stale on fault, and the verifier still
thinks the load overwrote it, so a program can leak it through a map.

Check ret >= 0 before calling add_exception_handler(), and pass rd for
LOAD_ACQ so the fault zeroes rd like a PROBE_MEM load. Return ret
unchanged for the zext skip.

Fixes: fb7cefabae ("riscv, bpf: Add support arena atomics for RV64")
Suggested-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20260720-bpf-riscv-fix-extable-v4-1-165c0b3b07d5@kylinos.cn
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

...

This commit is contained in:

Feng Jiang 2026-07-20 06:42:57 +00:00 • committed by Kumar Kartikeya Dwivedi

parent 2f2223a993

commit 5eb8921371

No known key found for this signature in database

GPG key ID: 472D377B63542F83

1 changed files with 6 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

arch/riscv/net/bpf_jit_comp64.c

View file