From fb4e3b33e3e7f13befdf9ee232e34818c6cc5fb9 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 24 Jun 2022 05:06:12 +0300 Subject: bpf: Fix for use-after-free bug in inline_bpf_loop As reported by Dan Carpenter, the following statements in inline_bpf_loop() might cause a use-after-free bug: struct bpf_prog *new_prog; // ... new_prog = bpf_patch_insn_data(env, position, insn_buf, *cnt); // ... env->prog->insnsi[call_insn_offset].imm = callback_offset; The bpf_patch_insn_data() might free the memory used by env->prog. Fixes: 1ade23711971 ("bpf: Inline calls to bpf_loop when callback is known") Reported-by: Dan Carpenter Signed-off-by: Eduard Zingerman Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220624020613.548108-2-eddyz87@gmail.com --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f228141c01c5..4938477912cd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14417,7 +14417,7 @@ static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env, /* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */ call_insn_offset = position + 12; callback_offset = callback_start - call_insn_offset - 1; - env->prog->insnsi[call_insn_offset].imm = callback_offset; + new_prog->insnsi[call_insn_offset].imm = callback_offset; return new_prog; } -- cgit v1.2.3