[PATCH] arm64: bpf: Fix UBSAN misaligned access in BPF JIT

Fuad Tabba
2026-02-24T09:31:30Z

struct bpf_plt contains a u64 'target' field. The BPF JIT allocator
was using an alignment of 4 bytes (sizeof(u32)), which could lead
to the 'target' field being misaligned in the JIT buffer.

Increase the alignment requirement to 8 bytes (sizeof(u64)) in
bpf_jit_binary_pack_alloc() to guarantee proper alignment for
struct bpf_plt.

Fixes: b2ad54e1533e9 ("bpf, arm64: Implement bpf_arch_text_poke() for arm64")
Signed-off-by: Fuad Tabba <tabba@google.com>
---
arch/arm64/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 356d33c7a4ae..adf84962d579 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -2119,7 +2119,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
extable_offset = round_up(prog_size + PLT_TARGET_SIZE, extable_align);
image_size = extable_offset + extable_size;
ro_header = bpf_jit_binary_pack_alloc(image_size, &ro_image_ptr,
- sizeof(u32), &header, &image_ptr,
+ sizeof(u64), &header, &image_ptr,
jit_fill_hole);
if (!ro_header) {
prog = orig_prog;
--
2.53.0.371.g1d285c8824-goog