From: Roberto Sassu roberto.sassu@huawei.com
stable inclusion from stable-v4.19.129 commit d52a190318f0901965f200f76eb28dd8426bbb25 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I69WIO CVE: NA
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commit 067a436b1b0aafa593344fddd711a755a58afb3b upstream.
This patch prevents the following oops:
[ 10.771813] BUG: kernel NULL pointer dereference, address: 0000000000000 [...] [ 10.779790] RIP: 0010:ima_match_policy+0xf7/0xb80 [...] [ 10.798576] Call Trace: [ 10.798993] ? ima_lsm_policy_change+0x2b0/0x2b0 [ 10.799753] ? inode_init_owner+0x1a0/0x1a0 [ 10.800484] ? _raw_spin_lock+0x7a/0xd0 [ 10.801592] ima_must_appraise.part.0+0xb6/0xf0 [ 10.802313] ? ima_fix_xattr.isra.0+0xd0/0xd0 [ 10.803167] ima_must_appraise+0x4f/0x70 [ 10.804004] ima_post_path_mknod+0x2e/0x80 [ 10.804800] do_mknodat+0x396/0x3c0
It occurs when there is a failure during IMA initialization, and ima_init_policy() is not called. IMA hooks still call ima_match_policy() but ima_rules is NULL. This patch prevents the crash by directly assigning the ima_default_policy pointer to ima_rules when ima_rules is defined. This wouldn't alter the existing behavior, as ima_rules is always set at the end of ima_init_policy().
Cc: stable@vger.kernel.org # 3.7.x Fixes: 07f6a79415d7d ("ima: add appraise action keywords and default rules") Reported-by: Takashi Iwai tiwai@suse.de Signed-off-by: Roberto Sassu roberto.sassu@huawei.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Lu Jialin lujialin4@huawei.com Reviewed-by: GUO zihua guozihua@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Reviewed-by: Wang Weiyang wangweiyang2@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- security/integrity/ima/ima_policy.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 6cc862ce3563..d71273898d40 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -196,7 +196,7 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { static LIST_HEAD(ima_default_rules); static LIST_HEAD(ima_policy_rules); static LIST_HEAD(ima_temp_rules); -static struct list_head *ima_rules; +static struct list_head *ima_rules = &ima_default_rules;
static int ima_policy __initdata;
@@ -655,7 +655,6 @@ void __init ima_init_policy(void) temp_ima_appraise |= IMA_APPRAISE_POLICY; }
- ima_rules = &ima_default_rules; ima_update_policy_flag(); }