From 32bf08a6257b9c7380dcd040af3c0858eee3ef05 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 20 Oct 2014 14:54:57 -0700 Subject: [PATCH] bpf: fix bug in eBPF verifier while comparing for verifier state equivalency the comparison was missing a check for uninitialized register. Make sure it does so and add a testcase. Fixes: f1bca824dabb ("bpf: add search pruning optimization to verifier") Cc: Hannes Frederic Sowa Signed-off-by: Alexei Starovoitov Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 3 ++- samples/bpf/test_verifier.c | 11 +++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 801f5f3b9307..9f81818f2941 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1409,7 +1409,8 @@ static bool states_equal(struct verifier_state *old, struct verifier_state *cur) if (memcmp(&old->regs[i], &cur->regs[i], sizeof(old->regs[0])) != 0) { if (old->regs[i].type == NOT_INIT || - old->regs[i].type == UNKNOWN_VALUE) + (old->regs[i].type == UNKNOWN_VALUE && + cur->regs[i].type != NOT_INIT)) continue; return false; } diff --git a/samples/bpf/test_verifier.c b/samples/bpf/test_verifier.c index f44ef11f65a7..eb4bec0ad8af 100644 --- a/samples/bpf/test_verifier.c +++ b/samples/bpf/test_verifier.c @@ -208,6 +208,17 @@ static struct bpf_test tests[] = { .errstr = "R0 !read_ok", .result = REJECT, }, + { + "program doesn't init R0 before exit in all branches", + .insns = { + BPF_JMP_IMM(BPF_JGE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 2), + BPF_EXIT_INSN(), + }, + .errstr = "R0 !read_ok", + .result = REJECT, + }, { "stack out of bounds", .insns = { -- 2.20.1