bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types

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@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7d62fd576089bbc06d837cceb8a37e1964c16d93..7df5c29293a4e412e2f6d221499b5e67b26b29e8 100644 (file)
--- 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;
@@ -9340,15 +9346,15 @@ 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,