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bpf: limit the number of levels of a nested struct type.

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Limit the number of levels looking into struct types to avoid running out
of stack space.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240523174202.461236-7-thinker.li@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kui-Feng Lee 2024-05-23 10:41:59 -07:00 committed by Alexei Starovoitov
parent 64e8ee8148
commit f19caf57d8
1 changed files with 19 additions and 11 deletions
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30
kernel/bpf/btf.c
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@ -3536,7 +3536,8 @@ static int btf_repeat_fields(struct btf_field_info *info,
static int btf_find_struct_field(const struct btf *btf,
const struct btf_type *t, u32 field_mask,
struct btf_field_info *info, int info_cnt);
struct btf_field_info *info, int info_cnt,
u32 level);
/* Find special fields in the struct type of a field.
*
@ -3547,11 +3548,15 @@ static int btf_find_struct_field(const struct btf *btf,
static int btf_find_nested_struct(const struct btf *btf, const struct btf_type *t,
u32 off, u32 nelems,
u32 field_mask, struct btf_field_info *info,
int info_cnt)
int info_cnt, u32 level)
{
int ret, err, i;
ret = btf_find_struct_field(btf, t, field_mask, info, info_cnt);
level++;
if (level >= MAX_RESOLVE_DEPTH)
return -E2BIG;
ret = btf_find_struct_field(btf, t, field_mask, info, info_cnt, level);
if (ret <= 0)
return ret;
@ -3579,7 +3584,8 @@ static int btf_find_field_one(const struct btf *btf,
int var_idx,
u32 off, u32 expected_size,
u32 field_mask, u32 *seen_mask,
struct btf_field_info *info, int info_cnt)
struct btf_field_info *info, int info_cnt,
u32 level)
{
int ret, align, sz, field_type;
struct btf_field_info tmp;
@ -3607,7 +3613,7 @@ static int btf_find_field_one(const struct btf *btf,
if (expected_size && expected_size != sz * nelems)
return 0;
ret = btf_find_nested_struct(btf, var_type, off, nelems, field_mask,
&info[0], info_cnt);
&info[0], info_cnt, level);
return ret;
}
@ -3668,7 +3674,8 @@ static int btf_find_field_one(const struct btf *btf,
static int btf_find_struct_field(const struct btf *btf,
const struct btf_type *t, u32 field_mask,
struct btf_field_info *info, int info_cnt)
struct btf_field_info *info, int info_cnt,
u32 level)
{
int ret, idx = 0;
const struct btf_member *member;
@ -3687,7 +3694,7 @@ static int btf_find_struct_field(const struct btf *btf,
ret = btf_find_field_one(btf, t, member_type, i,
off, 0,
field_mask, &seen_mask,
&info[idx], info_cnt - idx);
&info[idx], info_cnt - idx, level);
if (ret < 0)
return ret;
idx += ret;
@ -3697,7 +3704,7 @@ static int btf_find_struct_field(const struct btf *btf,
static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
u32 field_mask, struct btf_field_info *info,
int info_cnt)
int info_cnt, u32 level)
{
int ret, idx = 0;
const struct btf_var_secinfo *vsi;
@ -3710,7 +3717,8 @@ static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
off = vsi->offset;
ret = btf_find_field_one(btf, var, var_type, -1, off, vsi->size,
field_mask, &seen_mask,
&info[idx], info_cnt - idx);
&info[idx], info_cnt - idx,
level);
if (ret < 0)
return ret;
idx += ret;
@ -3723,9 +3731,9 @@ static int btf_find_field(const struct btf *btf, const struct btf_type *t,
int info_cnt)
{
if (__btf_type_is_struct(t))
return btf_find_struct_field(btf, t, field_mask, info, info_cnt);
return btf_find_struct_field(btf, t, field_mask, info, info_cnt, 0);
else if (btf_type_is_datasec(t))
return btf_find_datasec_var(btf, t, field_mask, info, info_cnt);
return btf_find_datasec_var(btf, t, field_mask, info, info_cnt, 0);
return -EINVAL;
}