kdb: Use strscpy with destination buffer size

[ Upstream commit c2b94c72d93d0929f48157eef128c4f9d2e603ce ]

gcc 8.1.0 warns with:

kernel/debug/kdb/kdb_support.c: In function ‘kallsyms_symbol_next’:
kernel/debug/kdb/kdb_support.c:239:4: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
     strncpy(prefix_name, name, strlen(name)+1);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/debug/kdb/kdb_support.c:239:31: note: length computed here

Use strscpy() with the destination buffer size, and use ellipses when
displaying truncated symbols.

v2: Use strscpy()

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jonathan Toppins <jtoppins@redhat.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: kgdb-bugreport@lists.sourceforge.net
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index ed5d349..6a4b414 100644 (file)
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -216,7 +216,7 @@ static char *kdb_read(char *buffer, size_t bufsize)
        int count;
        int i;
        int diag, dtab_count;
-       int key;
+       int key, buf_size, ret;
 
 
        diag = kdbgetintenv("DTABCOUNT", &dtab_count);
@@ -336,9 +336,8 @@ poll_again:
                else
                        p_tmp = tmpbuffer;
                len = strlen(p_tmp);
-               count = kallsyms_symbol_complete(p_tmp,
-                                                sizeof(tmpbuffer) -
-                                                (p_tmp - tmpbuffer));
+               buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
+               count = kallsyms_symbol_complete(p_tmp, buf_size);
                if (tab == 2 && count > 0) {
                        kdb_printf("\n%d symbols are found.", count);
                        if (count > dtab_count) {
@@ -350,9 +349,13 @@ poll_again:
                        }
                        kdb_printf("\n");
                        for (i = 0; i < count; i++) {
-                               if (WARN_ON(!kallsyms_symbol_next(p_tmp, i)))
+                               ret = kallsyms_symbol_next(p_tmp, i, buf_size);
+                               if (WARN_ON(!ret))
                                        break;
-                               kdb_printf("%s ", p_tmp);
+                               if (ret != -E2BIG)
+                                       kdb_printf("%s ", p_tmp);
+                               else
+                                       kdb_printf("%s... ", p_tmp);
                                *(p_tmp + len) = '\0';
                        }
                        if (i >= dtab_count)

diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index fc224fb..f2158e4 100644 (file)
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -83,7 +83,7 @@ typedef struct __ksymtab {
                unsigned long sym_start;
                unsigned long sym_end;
                } kdb_symtab_t;
-extern int kallsyms_symbol_next(char *prefix_name, int flag);
+extern int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size);
 extern int kallsyms_symbol_complete(char *prefix_name, int max_len);
 
 /* Exported Symbols for kernel loadable modules to use. */

diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
index 84422d2..014f6fb 100644 (file)
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -221,11 +221,13 @@ int kallsyms_symbol_complete(char *prefix_name, int max_len)
  * Parameters:
  *     prefix_name     prefix of a symbol name to lookup
  *     flag    0 means search from the head, 1 means continue search.
+ *     buf_size        maximum length that can be written to prefix_name
+ *                     buffer
  * Returns:
  *     1 if a symbol matches the given prefix.
  *     0 if no string found
  */
-int kallsyms_symbol_next(char *prefix_name, int flag)
+int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
 {
        int prefix_len = strlen(prefix_name);
        static loff_t pos;
@@ -235,10 +237,8 @@ int kallsyms_symbol_next(char *prefix_name, int flag)
                pos = 0;
 
        while ((name = kdb_walk_kallsyms(&pos))) {
-               if (strncmp(name, prefix_name, prefix_len) == 0) {
-                       strncpy(prefix_name, name, strlen(name)+1);
-                       return 1;
-               }
+               if (!strncmp(name, prefix_name, prefix_len))
+                       return strscpy(prefix_name, name, buf_size);
        }
        return 0;
 }