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bpf: fix bug in eBPF verifier

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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: f1bca824da ("bpf: add search pruning optimization to verifier")
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-10-20 14:54:57 -07:00 committed by David S. Miller
parent 78fd1d0ab0
commit 32bf08a625
2 changed files with 13 additions and 1 deletions
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3
kernel/bpf/verifier.c
View file

@ -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;
}

11
samples/bpf/test_verifier.c
View file

@ -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 = {