From: Peter Collingbourne pcc@google.com
[ Upstream commit a552e2ef5fd1a6c78267cd4ec5a9b49aa11bbb1c ]
When BPF_TRAMP_F_CALL_ORIG is enabled, the address of a bpf_tramp_image struct on the stack is passed during the size calculation pass and an address on the heap is passed during code generation. This may cause a heap buffer overflow if the heap address is tagged because emit_a64_mov_i64() will emit longer code than it did during the size calculation pass. The same problem could occur without tag-based KASAN if one of the 16-bit words of the stack address happened to be all-ones during the size calculation pass. Fix the problem by assuming the worst case (4 instructions) when calculating the size of the bpf_tramp_image address emission.
Fixes: 19d3c179a377 ("bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG") Signed-off-by: Peter Collingbourne pcc@google.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Xu Kuohai xukuohai@huawei.com Link: https://linux-review.googlesource.com/id/I1496f2bc24fba7a1d492e16e2b94cf4371... Link: https://lore.kernel.org/bpf/20241018221644.3240898-1-pcc@google.com [Minor context change fixed.] Signed-off-by: Bin Lan bin.lan.cn@windriver.com Signed-off-by: He Zhe zhe.he@windriver.com --- Build test passed. --- arch/arm64/net/bpf_jit_comp.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 3168343815b3..4afbbfc1d488 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1893,7 +1893,11 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, emit(A64_STR64I(A64_R(20), A64_SP, regs_off + 8), ctx);
if (flags & BPF_TRAMP_F_CALL_ORIG) { - emit_a64_mov_i64(A64_R(0), (const u64)im, ctx); + /* for the first pass, assume the worst case */ + if (!ctx->image) + ctx->idx += 4; + else + emit_a64_mov_i64(A64_R(0), (const u64)im, ctx); emit_call((const u64)__bpf_tramp_enter, ctx); }
@@ -1937,7 +1941,11 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im,
if (flags & BPF_TRAMP_F_CALL_ORIG) { im->ip_epilogue = ctx->image + ctx->idx; - emit_a64_mov_i64(A64_R(0), (const u64)im, ctx); + /* for the first pass, assume the worst case */ + if (!ctx->image) + ctx->idx += 4; + else + emit_a64_mov_i64(A64_R(0), (const u64)im, ctx); emit_call((const u64)__bpf_tramp_exit, ctx); }