1 files changed, 9 insertions, 1 deletions

diff --git a/src/fseccomp/syscall.c b/src/fseccomp/syscall.c
index 3b698d2dd..d31b719d6 100644
--- a/src/fseccomp/syscall.c
+++ b/src/fseccomp/syscall.c
@@ -497,9 +497,17 @@ int syscall_check_list(const char *slist, void (*callback)(int fd, int syscall,
                         syscall_check_list(new_list, callback, fd, arg, ptrarg);
                 }
                 else {
+                        bool negate = false;
+                        if (*ptr == '!') {
+                                negate = true;
+                                ptr++;
+                        }
                         syscall_process_name(ptr, &syscall_nr, &error_nr);
                         if (syscall_nr == -1) {;}
                         else if (callback != NULL) {
+                                if (negate) {
+                                        syscall_nr = -syscall_nr;
+                                }
                                 if (error_nr != -1 && fd != 0) {
                                         filter_add_errno(fd, syscall_nr, error_nr, ptrarg);
                                 }
@@ -522,7 +530,7 @@ static void find_syscall(int fd, int syscall, int arg, void *ptrarg) {
         (void)fd;
         (void) arg;
         SyscallCheckList *ptr = ptrarg;
-        if (syscall == ptr->syscall)
+        if (abs(syscall) == ptr->syscall)
                 ptr->found = true;
 }