6.1-stable review patch. If anyone has any objections, please let me know.
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From: Yonghong Song yonghong.song@linux.dev
commit dfce9cb3140592b886838e06f3e0c25fea2a9cae upstream.
Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") added support for new 32bit offset jmp instruction. Unfortunately, in function bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset (plus/minor a small delta) compares to 16-bit offset bound [S16_MIN, S16_MAX], which caused the following verification failure: $ ./test_progs-cpuv4 -t verif_scale_pyperf180 ... insn 10 cannot be patched due to 16-bit range ... libbpf: failed to load object 'pyperf180.bpf.o' scale_test:FAIL:expect_success unexpected error: -12 (errno 12) #405 verif_scale_pyperf180:FAIL
Note that due to recent llvm18 development, the patch [2] (already applied in bpf-next) needs to be applied to bpf tree for testing purpose.
The fix is rather simple. For 32bit offset branch insn, the adjusted offset compares to [S32_MIN, S32_MAX] and then verification succeeded.
[1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev [2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev
Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") Signed-off-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -365,14 +365,18 @@ static int bpf_adj_delta_to_imm(struct b static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old, s32 end_new, s32 curr, const bool probe_pass) { - const s32 off_min = S16_MIN, off_max = S16_MAX; + s64 off_min, off_max, off; s32 delta = end_new - end_old; - s32 off;
- if (insn->code == (BPF_JMP32 | BPF_JA)) + if (insn->code == (BPF_JMP32 | BPF_JA)) { off = insn->imm; - else + off_min = S32_MIN; + off_max = S32_MAX; + } else { off = insn->off; + off_min = S16_MIN; + off_max = S16_MAX; + }
if (curr < pos && curr + off + 1 >= end_old) off += delta;