Update libpostexecseccomp.c (#2851)

* Update libpostexecseccomp.c

Remove `if (size != 0)` condition, which is always true as there is a `if (size <= 0)` condition before.

Also note that if the `if (size <= 0)` condition wouldn't be there and `size` would be 0, there would have been an undefined behavior in due to division by zero in `(unsigned short) size / (unsigned short) sizeof(struct sock_filter);`.

Found with LGTM: https://lgtm.com/projects/g/netblue30/firejail/snapshot/961c4ca00425b60a7bc8543460031a8ebf3d8aa6/files/src/libpostexecseccomp/libpostexecseccomp.c#x838c24f710410160:1

1 files changed, 1 insertions, 3 deletions

diff --git a/src/libpostexecseccomp/libpostexecseccomp.c b/src/libpostexecseccomp/libpostexecseccomp.c
index 3983510ec..b2f64f18e 100644
--- a/src/libpostexecseccomp/libpostexecseccomp.c
+++ b/src/libpostexecseccomp/libpostexecseccomp.c
@@ -40,9 +40,7 @@ static void load_seccomp(void) {
                 return;
         }
         unsigned short entries = (unsigned short) size / (unsigned short) sizeof(struct sock_filter);
-        struct sock_filter *filter = MAP_FAILED;
-        if (size != 0)
-                filter = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+        struct sock_filter *filter = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
         close(fd);
 
         if (filter == MAP_FAILED) {