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authorAlexei Starovoitov <ast@fb.com>2016-04-06 19:39:21 -0700
committerDavid S. Miller <davem@davemloft.net>2016-04-10 22:43:18 -0400
commit4923ec0b10d998349c2ac4b38aa4674e539e6f92 (patch)
treeaabed2c261f40d5c2010493b3ed9a9088aa5f7a9 /kernel/bpf
parentae95d7126104591348d37aaf78c8325967e02386 (diff)
downloadlinux-sh-4923ec0b10d998349c2ac4b38aa4674e539e6f92.tar.gz
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')
-rw-r--r--kernel/bpf/verifier.c6
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 {