From: Haoran Jiang <jianghaoran@kylinos.cn> stable inclusion from stable-v6.6.103 commit 17c010fe45def335fe03a0718935416b04c7f349 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICWGIA CVE: CVE-2025-38723 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit cd39d9e6b7e4c58fa77783e7aedf7ada51d02ea3 upstream. The extra pass of bpf_int_jit_compile() skips JIT context initialization which essentially skips offset calculation leaving out_offset = -1, so the jmp_offset in emit_bpf_tail_call is calculated by "#define jmp_offset (out_offset - (cur_offset))" is a negative number, which is wrong. The final generated assembly are as follow. 54: bgeu $a2, $t1, -8 # 0x0000004c 58: addi.d $a6, $s5, -1 5c: bltz $a6, -16 # 0x0000004c 60: alsl.d $t2, $a2, $a1, 0x3 64: ld.d $t2, $t2, 264 68: beq $t2, $zero, -28 # 0x0000004c Before apply this patch, the follow test case will reveal soft lock issues. cd tools/testing/selftests/bpf/ ./test_progs --allow=tailcalls/tailcall_bpf2bpf_1 dmesg: watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [test_progs:25056] Cc: stable@vger.kernel.org Fixes: 5dc615520c4d ("LoongArch: Add BPF JIT support") Reviewed-by: Hengqi Chen <hengqi.chen@gmail.com> Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: arch/loongarch/net/bpf_jit.c [adjust context] Signed-off-by: Yuntao Liu <liuyuntao12@huawei.com> --- arch/loongarch/net/bpf_jit.c | 22 +++++----------------- 1 file changed, 5 insertions(+), 17 deletions(-) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 95fa56d5d5e3..ef20e21fe9fc 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -203,11 +203,9 @@ bool bpf_jit_supports_kfunc_call(void) return true; } -/* initialized on the first pass of build_body() */ -static int out_offset = -1; -static int emit_bpf_tail_call(struct jit_ctx *ctx) +static int emit_bpf_tail_call(struct jit_ctx *ctx, int insn) { - int off; + int off, tc_ninsn = 0; u8 tcc = tail_call_reg(ctx); u8 a1 = LOONGARCH_GPR_A1; u8 a2 = LOONGARCH_GPR_A2; @@ -217,7 +215,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) const int idx0 = ctx->idx; #define cur_offset (ctx->idx - idx0) -#define jmp_offset (out_offset - (cur_offset)) +#define jmp_offset (tc_ninsn - (cur_offset)) /* * a0: &ctx @@ -227,6 +225,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) * if (index >= array->map.max_entries) * goto out; */ + tc_ninsn = insn ? ctx->offset[insn+1] - ctx->offset[insn] : ctx->offset[0]; off = offsetof(struct bpf_array, map.max_entries); emit_insn(ctx, ldwu, t1, a1, off); /* bgeu $a2, $t1, jmp_offset */ @@ -258,15 +257,6 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) emit_insn(ctx, ldd, t3, t2, off); __build_epilogue(ctx, true); - /* out: */ - if (out_offset == -1) - out_offset = cur_offset; - if (cur_offset != out_offset) { - pr_err_once("tail_call out_offset = %d, expected %d!\n", - cur_offset, out_offset); - return -1; - } - return 0; toofar: @@ -853,7 +843,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext /* tail call */ case BPF_JMP | BPF_TAIL_CALL: mark_tail_call(ctx); - if (emit_bpf_tail_call(ctx) < 0) + if (emit_bpf_tail_call(ctx, i) < 0) return -EINVAL; break; @@ -1251,8 +1241,6 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) if (tmp_blinded) bpf_jit_prog_release_other(prog, prog == orig_prog ? tmp : orig_prog); - out_offset = -1; - return prog; out_free: -- 2.34.1