Fix: Missing RCU read locks in syscall_list_channel()

[lttng-tools.git] / src / bin / lttng-sessiond / syscall.c

diff --git a/src/bin/lttng-sessiond/syscall.c b/src/bin/lttng-sessiond/syscall.c
index ee7578051e2a12d3322cb6e3d9fd4ae2946da1a7..c38f8910940f0b8bb990034ed4fa0fcef0360fef 100644 (file)
--- a/src/bin/lttng-sessiond/syscall.c
+++ b/src/bin/lttng-sessiond/syscall.c
@@ -16,6 +16,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <common/bitfield.h>
 #include <common/common.h>
 #include <common/kernel-ctl/kernel-ctl.h>
@@ -35,7 +36,7 @@ static size_t syscall_table_nb_entry;
  * Populate the system call table using the kernel tracer.
  *
  * Return 0 on success and the syscall table is allocated. On error, a negative
- * value is returned and the syscall table is set to NULL.
+ * value is returned.
  */
 int syscall_init_table(void)
 {
@@ -82,6 +83,14 @@ int syscall_init_table(void)
 
                        /* Double memory size. */
                        new_nbmem = max(index, nbmem << 1);
+                       if (new_nbmem < nbmem) {
+                               /* Overflow, stop everything, something went really wrong. */
+                               ERR("Syscall listing memory size overflow. Stopping");
+                               free(syscall_table);
+                               syscall_table = NULL;
+                               ret = -EINVAL;
+                               goto error;
+                       }
 
                        DBG("Reallocating syscall table from %zu to %zu entries", nbmem,
                                        new_nbmem);
@@ -396,11 +405,14 @@ ssize_t syscall_list_channel(struct ltt_kernel_channel *kchan,
                        events = new_events;
                }
 
+               rcu_read_lock();
                ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name);
                if (ksyscall) {
                        update_event_syscall_bitness(events, i, ksyscall->index);
                        continue;
                }
+               ksyscall = NULL;
+               rcu_read_unlock();
 
                ret = add_syscall_to_ht(syscalls_ht, i, count);
                if (ret < 0) {
@@ -420,7 +432,10 @@ ssize_t syscall_list_channel(struct ltt_kernel_channel *kchan,
        return count;
 
 error:
+       rcu_read_lock();
        destroy_syscall_ht(syscalls_ht);
+       rcu_read_unlock();
+
        free(events);
        return ret;
 }