When BPF_TRAMP_F_CALL_ORIG is set, the trampoline calls
__bpf_tramp_enter() and __bpf_tramp_exit() functions, passing them the
struct bpf_tramp_image *im pointer as an argument in R0.
The trampoline generation code uses emit_addr_mov_i64() to emit
instructions for moving the bpf_tramp_image address into R0, but
emit_addr_mov_i64() assumes the address to be in the vmalloc() space and
uses only 48 bits. Because bpf_tramp_image is allocated using kzalloc(),
its address can use more than 48-bits, in this case the trampoline
will pass an invalid address to __bpf_tramp_enter/exit() causing a
kernel crash.
Fix this by using emit_a64_mov_i64() in place of emit_addr_mov_i64() as
it can work with addresses that are greater than 48-bits.
Fixes: efc9909fdce0 ("bpf, arm64: Add bpf trampoline for arm64")
Closes: https://lore.kernel.org/all/SJ0PR15MB461564D3F7E7A763498CA6A8CBDB2@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx>
---
arch/arm64/net/bpf_jit_comp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 720336d28856..1bf483ec971d 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -2141,7 +2141,7 @@ 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_addr_mov_i64(A64_R(0), (const u64)im, ctx);
+ emit_a64_mov_i64(A64_R(0), (const u64)im, ctx);
emit_call((const u64)__bpf_tramp_enter, ctx);
}
@@ -2185,7 +2185,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im,
if (flags & BPF_TRAMP_F_CALL_ORIG) {
im->ip_epilogue = ctx->ro_image + ctx->idx;
- emit_addr_mov_i64(A64_R(0), (const u64)im, ctx);
+ emit_a64_mov_i64(A64_R(0), (const u64)im, ctx);
emit_call((const u64)__bpf_tramp_exit, ctx);
}
--
2.40.1
