[PATCH 03/12] ima: Free the entire rule when deleting a list of rules

[Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>]

Use ima_free_rule() to fix memory leaks of allocated ima_rule_entry
members, such as .fsname and .keyrings, when deleting a list of rules.

This fixes a memory leak seen when loading by a valid rule that contains
an additional piece of allocated memory, such as an fsname, followed by
an invalid rule that triggers a policy load failure:

 # echo -e "dont_measure fsname=securityfs\nbad syntax" > \
    /sys/kernel/security/ima/policy
 -bash: echo: write error: Invalid argument
 # echo scan > /sys/kernel/debug/kmemleak
 # cat /sys/kernel/debug/kmemleak
 unreferenced object 0xffff9bab67ca12c0 (size 16):
   comm "tee", pid 684, jiffies 4295212803 (age 252.344s)
   hex dump (first 16 bytes):
     73 65 63 75 72 69 74 79 66 73 00 6b 6b 6b 6b a5  securityfs.kkkk.
   backtrace:
     [<00000000adc80b1b>] kstrdup+0x2e/0x60
     [<00000000d504cb0d>] ima_parse_add_rule+0x7d4/0x1020
     [<00000000444825ac>] ima_write_policy+0xab/0x1d0
     [<000000002b7f0d6c>] vfs_write+0xde/0x1d0
     [<0000000096feedcf>] ksys_write+0x68/0xe0
     [<0000000052b544a2>] do_syscall_64+0x56/0xa0
     [<000000007ead1ba7>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: f1b08bbcbdaf ("ima: define a new policy condition based on the filesystem name")
Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy")
Signed-off-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
---
 security/integrity/ima/ima_policy.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 1320333201c6..94ca3b8abb69 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1431,15 +1431,11 @@ ssize_t ima_parse_add_rule(char *rule)
 void ima_delete_rules(void)
 {
 	struct ima_rule_entry *entry, *tmp;
-	int i;
 
 	temp_ima_appraise = 0;
 	list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
-		for (i = 0; i < MAX_LSM_RULES; i++)
-			kfree(entry->lsm[i].args_p);
-
 		list_del(&entry->list);
-		kfree(entry);
+		ima_free_rule(entry);
 	}
 }
 
-- 
2.25.1