Fix: don't allow disabling syscalls when none are enabled

[lttng-modules.git] / lttng-syscalls.c

diff --git a/lttng-syscalls.c b/lttng-syscalls.c
index cba0016007d95c190fc4a4987c0f727e8a7cefeb..5cac721200bb8aa5cab44ffcfa281e380d7ccfe1 100644 (file)
--- a/lttng-syscalls.c
+++ b/lttng-syscalls.c
@@ -1036,6 +1036,8 @@ int lttng_syscall_filter_disable(struct lttng_channel *chan,
        WARN_ON_ONCE(!chan->sc_table);
 
        if (!chan->sc_filter) {
+               if (!chan->syscall_all)
+                       return -EEXIST;
                filter = kzalloc(sizeof(struct lttng_syscall_filter),
                                GFP_KERNEL);
                if (!filter)
@@ -1048,6 +1050,14 @@ int lttng_syscall_filter_disable(struct lttng_channel *chan,
        }
 
        if (!name) {
+               /* Fail if all syscalls are already disabled. */
+               if (bitmap_empty(filter->sc, NR_syscalls)
+                       && bitmap_empty(filter->sc_compat,
+                               NR_compat_syscalls)) {
+                       ret = -EEXIST;
+                       goto error;
+               }
+
                /* Disable all system calls */
                bitmap_clear(filter->sc, 0, NR_syscalls);
                bitmap_clear(filter->sc_compat, 0, NR_compat_syscalls);
@@ -1060,18 +1070,18 @@ int lttng_syscall_filter_disable(struct lttng_channel *chan,
                goto error;
        }
        if (syscall_nr >= 0) {
-               if (!test_bit(syscall_nr, chan->sc_filter->sc)) {
+               if (!test_bit(syscall_nr, filter->sc)) {
                        ret = -EEXIST;
                        goto error;
                }
-               bitmap_clear(chan->sc_filter->sc, syscall_nr, 1);
+               bitmap_clear(filter->sc, syscall_nr, 1);
        }
        if (compat_syscall_nr >= 0) {
-               if (!test_bit(compat_syscall_nr, chan->sc_filter->sc_compat)) {
+               if (!test_bit(compat_syscall_nr, filter->sc_compat)) {
                        ret = -EEXIST;
                        goto error;
                }
-               bitmap_clear(chan->sc_filter->sc_compat, compat_syscall_nr, 1);
+               bitmap_clear(filter->sc_compat, compat_syscall_nr, 1);
        }
 apply_filter:
        if (!chan->sc_filter)