From b138004ea0382bdc6d02599c39392651b4f63889 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 23 Jul 2013 17:38:42 -0400 Subject: [PATCH] SELinux: fix selinuxfs policy file on big endian systems The /sys/fs/selinux/policy file is not valid on big endian systems like ppc64 or s390. Let's see why: static int hashtab_cnt(void *key, void *data, void *ptr) { int *cnt = ptr; *cnt = *cnt + 1; return 0; } static int range_write(struct policydb *p, void *fp) { size_t nel; [...] /* count the number of entries in the hashtab */ nel = 0; rc = hashtab_map(p->range_tr, hashtab_cnt, &nel); if (rc) return rc; buf[0] = cpu_to_le32(nel); rc = put_entry(buf, sizeof(u32), 1, fp); So size_t is 64 bits. But then we pass a pointer to it as we do to hashtab_cnt. hashtab_cnt thinks it is a 32 bit int and only deals with the first 4 bytes. On x86_64 which is little endian, those first 4 bytes and the least significant, so this works out fine. On ppc64/s390 those first 4 bytes of memory are the high order bits. So at the end of the call to hashtab_map nel has a HUGE number. But the least significant 32 bits are all 0's. We then pass that 64 bit number to cpu_to_le32() which happily truncates it to a 32 bit number and does endian swapping. But the low 32 bits are all 0's. So no matter how many entries are in the hashtab, big endian systems always say there are 0 entries because I screwed up the counting. The fix is easy. Use a 32 bit int, as the hashtab_cnt expects, for nel. Signed-off-by: Eric Paris Signed-off-by: Paul Moore --- security/selinux/ss/policydb.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index 9cd9b7c661ec..3fc8969b499c 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -3200,9 +3200,8 @@ static int range_write_helper(void *key, void *data, void *ptr) static int range_write(struct policydb *p, void *fp) { - size_t nel; __le32 buf[1]; - int rc; + int rc, nel; struct policy_data pd; pd.p = p; -- 2.34.1