bpftool: Fix readlink usage in get_fd_type

[ Upstream commit 0053f7d39d491b6138d7c526876d13885cbb65f1 ]

The `readlink(path, buf, sizeof(buf))` call reads at most sizeof(buf)
bytes and *does not* append null-terminator to buf. With respect to
that, fix two pieces in get_fd_type:

1. Change the truncation check to contain sizeof(buf) rather than
   sizeof(path).
2. Append null-terminator to buf.

Reported by Coverity.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20250129071857.75182-1-vmalik@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Viktor Malik
2025-01-29 08:18:57 +01:00
committed by Greg Kroah-Hartman
parent 0e8eb91a49
commit 38d906f1c5

View File

@@ -461,10 +461,11 @@ int get_fd_type(int fd)
p_err("can't read link type: %s", strerror(errno));
return -1;
}
if (n == sizeof(path)) {
if (n == sizeof(buf)) {
p_err("can't read link type: path too long!");
return -1;
}
buf[n] = '\0';
if (strstr(buf, "bpf-map"))
return BPF_OBJ_MAP;