When checking malformed helper function signatures, also take other argument
types into account aside from just ARG_PTR_TO_UNINIT_MEM.
This concerns (formerly) ARG_PTR_TO_{INT,LONG} given uninitialized memory can
be passed there, too.
The func proto sanity check goes back to commit 435faee1aae9 ("bpf, verifier:
add ARG_PTR_TO_RAW_STACK type"), and its purpose was to detect wrong func protos
which had more than just one MEM_UNINIT-tagged type as arguments.
The reason more than one is currently not supported is as we mark stack slots with
STACK_MISC in check_helper_call() in case of raw mode based on meta.access_size to
allow uninitialized stack memory to be passed to helpers when they just write into
the buffer.
Probing for base type as well as MEM_UNINIT tagging ensures that other types do not
get missed (as it used to be the case for ARG_PTR_TO_{INT,LONG}).
Fixes: 57c3bb725a3d ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
v1 -> v2:
- new patch (Shung-Hsi)
v2 -> v3:
- base_type(type) was needed also
kernel/bpf/verifier.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3a0801933a79..a1bbe4b401af 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8291,6 +8291,12 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type)
type == ARG_CONST_SIZE_OR_ZERO;
}
+static bool arg_type_is_raw_mem(enum bpf_arg_type type)
+{
+ return base_type(type) == ARG_PTR_TO_MEM &&
+ type & MEM_UNINIT;
+}
+
static bool arg_type_is_release(enum bpf_arg_type type)
{
return type & OBJ_RELEASE;
@@ -9343,15 +9349,15 @@ static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
int count = 0;
- if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
+ if (arg_type_is_raw_mem(fn->arg1_type))
count++;
- if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
+ if (arg_type_is_raw_mem(fn->arg2_type))
count++;
- if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
+ if (arg_type_is_raw_mem(fn->arg3_type))
count++;
- if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
+ if (arg_type_is_raw_mem(fn->arg4_type))
count++;
- if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
+ if (arg_type_is_raw_mem(fn->arg5_type))
count++;
/* We only support one arg being in raw mode at the moment,
--
2.43.0
