On Tue, Nov 5, 2024 at 1:46 PM Christian Göttsche
<cgoettsche@xxxxxxxxxxxxx> wrote:
>
> From: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
>
> openattr() supplies the simplementation for the getcon(3) interface
implementation
> family. Use a short local buffer instead of descend into memory
"Use a short local buffer instead of dynamic memory allocation"?
> allocation.
>
> Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
> ---
> libselinux/src/procattr.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/libselinux/src/procattr.c b/libselinux/src/procattr.c
> index ddcc7f8d..ee1f48af 100644
> --- a/libselinux/src/procattr.c
> +++ b/libselinux/src/procattr.c
> @@ -86,32 +86,32 @@ static void init_procattr(void)
> static int openattr(pid_t pid, const char *attr, int flags)
> {
> int fd, rc;
> - char *path;
> + char path[56]; /* must hold "/proc/self/task/%d/attr/sockcreate" */
Why 56? I understand that sockcreate is the largest attr, but it looks
to me like you are giving way more space than is needed for the pid. I
am just curious. Maybe I am missing something.
Thanks,
Jim
> pid_t tid;
>
> if (pid > 0) {
> - rc = asprintf(&path, "/proc/%d/attr/%s", pid, attr);
> + rc = snprintf(path, sizeof(path), "/proc/%d/attr/%s", pid, attr);
> } else if (pid == 0) {
> - rc = asprintf(&path, "/proc/thread-self/attr/%s", attr);
> - if (rc < 0)
> + rc = snprintf(path, sizeof(path), "/proc/thread-self/attr/%s", attr);
> + if (rc < 0 || (size_t)rc >= sizeof(path)) {
> + errno = EOVERFLOW;
> return -1;
> + }
> fd = open(path, flags | O_CLOEXEC);
> if (fd >= 0 || errno != ENOENT)
> - goto out;
> - free(path);
> + return fd;
> tid = selinux_gettid();
> - rc = asprintf(&path, "/proc/self/task/%d/attr/%s", tid, attr);
> + rc = snprintf(path, sizeof(path), "/proc/self/task/%d/attr/%s", tid, attr);
> } else {
> errno = EINVAL;
> return -1;
> }
> - if (rc < 0)
> + if (rc < 0 || (size_t)rc >= sizeof(path)) {
> + errno = EOVERFLOW;
> return -1;
> + }
>
> - fd = open(path, flags | O_CLOEXEC);
> -out:
> - free(path);
> - return fd;
> + return open(path, flags | O_CLOEXEC);
> }
>
> static int getprocattrcon_raw(char **context, pid_t pid, const char *attr,
> --
> 2.45.2
>
>
