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Subject[PATCH 4.9 059/101] bpf/verifier: Pass instruction index to check_mem_access() and check_xadd()
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben.hutchings@codethink.co.uk>

Extracted from commit 31fd85816dbe "bpf: permits narrower load from
bpf program context fields".

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/bpf/verifier.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -745,7 +745,7 @@ static int check_ptr_alignment(struct bp
* if t==write && value_regno==-1, some unknown value is stored into memory
* if t==read && value_regno==-1, don't care what we read from memory
*/
-static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off,
+static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off,
int bpf_size, enum bpf_access_type t,
int value_regno)
{
@@ -875,7 +875,7 @@ static int check_mem_access(struct bpf_v
return err;
}

-static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn)
+static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
{
struct bpf_reg_state *regs = env->cur_state.regs;
int err;
@@ -908,13 +908,13 @@ static int check_xadd(struct bpf_verifie
}

/* check whether atomic_add can read the memory */
- err = check_mem_access(env, insn->dst_reg, insn->off,
+ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_READ, -1);
if (err)
return err;

/* check whether atomic_add can write into the same memory */
- return check_mem_access(env, insn->dst_reg, insn->off,
+ return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE, -1);
}

@@ -1270,7 +1270,7 @@ static int check_call(struct bpf_verifie
* is inferred from register state.
*/
for (i = 0; i < meta.access_size; i++) {
- err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1);
+ err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1);
if (err)
return err;
}
@@ -2936,7 +2936,7 @@ static int do_check(struct bpf_verifier_
/* check that memory (src_reg + off) is readable,
* the state of dst_reg will be updated by this func
*/
- err = check_mem_access(env, insn->src_reg, insn->off,
+ err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
BPF_SIZE(insn->code), BPF_READ,
insn->dst_reg);
if (err)
@@ -2976,7 +2976,7 @@ static int do_check(struct bpf_verifier_
enum bpf_reg_type *prev_dst_type, dst_reg_type;

if (BPF_MODE(insn->code) == BPF_XADD) {
- err = check_xadd(env, insn);
+ err = check_xadd(env, insn_idx, insn);
if (err)
return err;
insn_idx++;
@@ -2995,7 +2995,7 @@ static int do_check(struct bpf_verifier_
dst_reg_type = regs[insn->dst_reg].type;

/* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, insn->dst_reg, insn->off,
+ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE,
insn->src_reg);
if (err)
@@ -3030,7 +3030,7 @@ static int do_check(struct bpf_verifier_
}

/* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, insn->dst_reg, insn->off,
+ err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE,
-1);
if (err)

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