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selinux: fix NULL dereference in policydb_destroy() 

The conversion to kvmalloc() forgot to account for the possibility that
p->type_attr_map_array might be null in policydb_destroy().

Fix this by destroying its contents only if it is not NULL.

Also make sure ebitmap_init() is called on all entries before
policydb_destroy() can be called. Right now this is a no-op, because
both kvcalloc() and ebitmap_init() just zero out the whole struct, but
let's rather not rely on a specific implementation.

Reported-by: syzbot+a57b2aff60832666fc28@syzkaller.appspotmail.com
Fixes: acdf52d97f ("selinux: convert to kvmalloc")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Ondrej Mosnacek 2019-03-17 14:46:53 +01:00 committed by Paul Moore
parent 9e98c678c2
commit 6a1afffb08
1 changed files with 9 additions and 4 deletions
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13
security/selinux/ss/policydb.c
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@ -828,9 +828,11 @@ void policydb_destroy(struct policydb *p)
hashtab_map(p->range_tr, range_tr_destroy, NULL);
hashtab_destroy(p->range_tr);
for (i = 0; i < p->p_types.nprim; i++)
ebitmap_destroy(&p->type_attr_map_array[i]);
kvfree(p->type_attr_map_array);
if (p->type_attr_map_array) {
for (i = 0; i < p->p_types.nprim; i++)
ebitmap_destroy(&p->type_attr_map_array[i]);
kvfree(p->type_attr_map_array);
}
ebitmap_destroy(&p->filename_trans_ttypes);
ebitmap_destroy(&p->policycaps);
@ -2496,10 +2498,13 @@ int policydb_read(struct policydb *p, void *fp)
if (!p->type_attr_map_array)
goto bad;
/* just in case ebitmap_init() becomes more than just a memset(0): */
for (i = 0; i < p->p_types.nprim; i++)
ebitmap_init(&p->type_attr_map_array[i]);
for (i = 0; i < p->p_types.nprim; i++) {
struct ebitmap *e = &p->type_attr_map_array[i];
ebitmap_init(e);
if (p->policyvers >= POLICYDB_VERSION_AVTAB) {
rc = ebitmap_read(e, fp);
if (rc)