bpf: Always use maximal size for copy_array()

[ Upstream commit 45435d8da71f9f3e6860e6e6ea9667b6ec17ec64 ]

Instead of counting on prior allocations to have sized allocations to
the next kmalloc bucket size, always perform a krealloc that is at least
ksize(dst) in size (which is a no-op), so the size can be correctly
tracked by all the various allocation size trackers (KASAN,
__alloc_size, etc).

Reported-by: Hyunwoo Kim <v4bel@theori.io>
Link: https://lore.kernel.org/bpf/20221223094551.GA1439509@ubuntu
Fixes: ceb35b666d42 ("bpf/verifier: Use kmalloc_size_roundup() to match ksize() usage")
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: bpf@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221223182836.never.866-kees@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 242fe30..b4d5b34 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1000,6 +1000,8 @@ static void print_insn_state(struct bpf_verifier_env *env,
  */
 static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
 {
+       size_t alloc_bytes;
+       void *orig = dst;
        size_t bytes;
 
        if (ZERO_OR_NULL_PTR(src))
@@ -1008,11 +1010,11 @@ static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t
        if (unlikely(check_mul_overflow(n, size, &bytes)))
                return NULL;
 
-       if (ksize(dst) < ksize(src)) {
-               kfree(dst);
-               dst = kmalloc_track_caller(kmalloc_size_roundup(bytes), flags);
-               if (!dst)
-                       return NULL;
+       alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes));
+       dst = krealloc(orig, alloc_bytes, flags);
+       if (!dst) {
+               kfree(orig);
+               return NULL;
        }
 
        memcpy(dst, src, bytes);