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bpf: fix partial copy of map_ptr when dst is scalar

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ALU operations on pointers such as scalar_reg += map_value_ptr are
handled in adjust_ptr_min_max_vals(). Problem is however that map_ptr
and range in the register state share a union, so transferring state
through dst_reg->range = ptr_reg->range is just buggy as any new
map_ptr in the dst_reg is then truncated (or null) for subsequent
checks. Fix this by adding a raw member and use it for copying state
over to dst_reg.

Fixes: f1174f77b5 ("bpf/verifier: rework value tracking")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Edward Cree <ecree@solarflare.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-11-01 00:05:52 +01:00 committed by Alexei Starovoitov
parent 3615353218
commit 0962590e55
2 changed files with 9 additions and 4 deletions
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3
include/linux/bpf_verifier.h
View File

@ -51,6 +51,9 @@ struct bpf_reg_state {
* PTR_TO_MAP_VALUE_OR_NULL
*/
struct bpf_map *map_ptr;
/* Max size from any of the above. */
unsigned long raw;
};
/* Fixed part of pointer offset, pointer types only */
s32 off;

10
kernel/bpf/verifier.c
View File

@ -3046,7 +3046,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
dst_reg->umax_value = umax_ptr;
dst_reg->var_off = ptr_reg->var_off;
dst_reg->off = ptr_reg->off + smin_val;
dst_reg->range = ptr_reg->range;
dst_reg->raw = ptr_reg->raw;
break;
}
/* A new variable offset is created. Note that off_reg->off
@ -3076,10 +3076,11 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
}
dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
dst_reg->off = ptr_reg->off;
dst_reg->raw = ptr_reg->raw;
if (reg_is_pkt_pointer(ptr_reg)) {
dst_reg->id = ++env->id_gen;
/* something was added to pkt_ptr, set range to zero */
dst_reg->range = 0;
dst_reg->raw = 0;
}
break;
case BPF_SUB:
@ -3108,7 +3109,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
dst_reg->var_off = ptr_reg->var_off;
dst_reg->id = ptr_reg->id;
dst_reg->off = ptr_reg->off - smin_val;
dst_reg->range = ptr_reg->range;
dst_reg->raw = ptr_reg->raw;
break;
}
/* A new variable offset is created. If the subtrahend is known
@ -3134,11 +3135,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
}
dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
dst_reg->off = ptr_reg->off;
dst_reg->raw = ptr_reg->raw;
if (reg_is_pkt_pointer(ptr_reg)) {
dst_reg->id = ++env->id_gen;
/* something was added to pkt_ptr, set range to zero */
if (smin_val < 0)
dst_reg->range = 0;
dst_reg->raw = 0;
}
break;
case BPF_AND: