contrib/plugins/execlog: Add tab to the separator search of insn_disas

Currently, execlog searches for a space separator between the
instruction mnemonic and operands, but some disassemblers, e.g. Alpha's,
use a tab separator instead; this results in a null pointer being passed
as the haystack in g_strstr during a subsequent register search, i.e.
undefined behavior, because of a missing null check.

This patch adds tab to the separator search and a null check on the
result.

Also, an affected pointer is changed to const.

Lastly, a break statement was added to immediately terminate the
register search when a user-requested register is found in the current
instruction as a trivial optimization, because searching for the
remaining requested registers is unnecessary once one is found.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Yodel Eldar <yodel.eldar@gmail.com>
Message-ID: <20250630164124.26315-2-yodel.eldar@gmail.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-ID: <20250710104531.3099313-4-alex.bennee@linaro.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c
index d67d010761..06ec76d6e9 100644
--- a/contrib/plugins/execlog.c
+++ b/contrib/plugins/execlog.c
@@ -232,12 +232,15 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
          */
         if (disas_assist && rmatches) {
             check_regs_next = false;
-            gchar *args = g_strstr_len(insn_disas, -1, " ");
-            for (int n = 0; n < all_reg_names->len; n++) {
-                gchar *reg = g_ptr_array_index(all_reg_names, n);
-                if (g_strrstr(args, reg)) {
-                    check_regs_next = true;
-                    skip = false;
+            g_auto(GStrv) args = g_strsplit_set(insn_disas, " \t", 2);
+            if (args && args[1]) {
+                for (int n = 0; n < all_reg_names->len; n++) {
+                    const gchar *reg = g_ptr_array_index(all_reg_names, n);
+                    if (g_strrstr(args[1], reg)) {
+                        check_regs_next = true;
+                        skip = false;
+                        break;
+                    }
                 }
             }
         }