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| author |  Alexei Starovoitov <ast@fb.com>
| 2016-04-06 19:39:21 -0700 |
|---|---|---|
| committer |  David S. Miller <davem@davemloft.net>
| 2016-04-10 22:43:18 -0400 |
| commit | 4923ec0b10d998349c2ac4b38aa4674e539e6f92 (patch) | |
| tree | aabed2c261f40d5c2010493b3ed9a9088aa5f7a9 /kernel/bpf/verifier.c | |
| parent | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net (diff) | |
| download | linux-4923ec0b10d998349c2ac4b38aa4674e539e6f92.tar.gz linux-4923ec0b10d998349c2ac4b38aa4674e539e6f92.tar.bz2 linux-4923ec0b10d998349c2ac4b38aa4674e539e6f92.zip | |
bpf: simplify verifier register state assignments
verifier is using the following structure to track the state of registers:
struct reg_state {
enum bpf_reg_type type;
union {
int imm;
struct bpf_map *map_ptr;
};
};
and later on in states_equal() does memcmp(&old->regs[i], &cur->regs[i],..)
to find equivalent states.
Throughout the code of verifier there are assignements to 'imm' and 'map_ptr'
fields and it's not obvious that most of the assignments into 'imm' don't
need to clear extra 4 bytes (like mark_reg_unknown_value() does) to make sure
that memcmp doesn't go over junk left from 'map_ptr' assignment.
Simplify the code by converting 'int' into 'long'
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8233021538d3..6c5d7cd4cb0e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -142,7 +142,7 @@ struct reg_state { enum bpf_reg_type type; union { /* valid when type == CONST_IMM | PTR_TO_STACK */ - int imm; + long imm; /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | * PTR_TO_MAP_VALUE_OR_NULL @@ -263,7 +263,7 @@ static void print_verifier_state(struct verifier_env *env) continue; verbose(" R%d=%s", i, reg_type_str[t]); if (t == CONST_IMM || t == PTR_TO_STACK) - verbose("%d", env->cur_state.regs[i].imm); + verbose("%ld", env->cur_state.regs[i].imm); else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || t == PTR_TO_MAP_VALUE_OR_NULL) verbose("(ks=%d,vs=%d)", @@ -480,7 +480,6 @@ static void init_reg_state(struct reg_state *regs) for (i = 0; i < MAX_BPF_REG; i++) { regs[i].type = NOT_INIT; regs[i].imm = 0; - regs[i].map_ptr = NULL; } /* frame pointer */ @@ -495,7 +494,6 @@ static void mark_reg_unknown_value(struct reg_state *regs, u32 regno) BUG_ON(regno >= MAX_BPF_REG); regs[regno].type = UNKNOWN_VALUE; regs[regno].imm = 0; - regs[regno].map_ptr = NULL; } enum reg_arg_type { |