From: Daniel Borkmann <daniel@iogearbox.net>
To: ast@kernel.org
Cc: netdev@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>,
Edward Cree <ecree@solarflare.com>
Subject: [PATCH bpf 1/4] bpf: fix partial copy of map_ptr when dst is scalar
Date: Thu, 1 Nov 2018 00:05:52 +0100 [thread overview]
Message-ID: <20181031230555.3371-2-daniel@iogearbox.net> (raw)
In-Reply-To: <20181031230555.3371-1-daniel@iogearbox.net>
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: f1174f77b50c ("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>
---
include/linux/bpf_verifier.h | 3 +++
kernel/bpf/verifier.c | 10 ++++++----
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 9e8056e..d93e897 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -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;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 171a2c8..774fa40 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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:
--
2.9.5
next prev parent reply other threads:[~2018-11-01 8:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 23:05 [PATCH bpf 0/4] BPF fixes and tests Daniel Borkmann
2018-10-31 23:05 ` Daniel Borkmann [this message]
2018-11-01 19:17 ` [PATCH bpf 1/4] bpf: fix partial copy of map_ptr when dst is scalar Edward Cree
2018-11-01 19:18 ` Arnaldo Carvalho de Melo
2018-10-31 23:05 ` [PATCH bpf 2/4] bpf: don't set id on after map lookup with ptr_to_map_val return Daniel Borkmann
2018-11-01 1:11 ` Roman Gushchin
2018-10-31 23:05 ` [PATCH bpf 3/4] bpf: add various test cases to test_verifier Daniel Borkmann
2018-10-31 23:05 ` [PATCH bpf 4/4] bpf: test make sure to run unpriv test cases in test_verifier Daniel Borkmann
2018-11-01 0:08 ` [PATCH bpf 0/4] BPF fixes and tests Alexei Starovoitov
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