4.14-stable review patch. If anyone has any objections, please let me know.
------------------
commit 0962590e553331db2cc0aef2dc35c57f6300dbbe upstream.
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@xxxxxxxxxxxxx>
Cc: Edward Cree <ecree@xxxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Edward Cree <ecree@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 73bec75b74c8..a3333004fd2b 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -50,6 +50,9 @@ 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 a0ffc62e7677..013b0cd1958e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1935,7 +1935,7 @@ 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
@@ -1965,10 +1965,11 @@ 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 (ptr_reg->type == PTR_TO_PACKET) {
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:
@@ -1999,7 +2000,7 @@ 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
@@ -2025,11 +2026,12 @@ 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 (ptr_reg->type == PTR_TO_PACKET) {
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:
--
2.17.1
