tracing/uprobe: Replace strlcpy() with strscpy()

strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().

The negative return value is already handled by this code so no new
handling is needed here.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
Link: https://github.com/KSPP/linux/issues/89
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: linux-trace-kernel@vger.kernel.org
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20231130205607.work.463-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 99c051de412afa4d6a433d1250a7abbd0d2deb3f..a84b85d8aac12464b80312431e68ceb46c5b19c5 100644 (file)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -151,7 +151,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
                return -ENOMEM;
 
        if (addr == FETCH_TOKEN_COMM)
-               ret = strlcpy(dst, current->comm, maxlen);
+               ret = strscpy(dst, current->comm, maxlen);
        else
                ret = strncpy_from_user(dst, src, maxlen);
        if (ret >= 0) {