apparmor: policy_int make sure list heads are initialized before fail path

[ Upstream commit 3daad923a8685adb66087e0d819559b7eb6ba975 ]

If profile create fails before policy_init is complete the list heads
are not properly initialized causing profile_free() sanity checks to
trigger the following splat.

AppArmor WARN aa_policy_destroy: (((!list_empty(&policy->profiles) && (&policy->profiles)->prev != ((void *) 0x122 + (0xdead000000000000UL))))):
WARNING: security/apparmor/lib.c:509 at aa_policy_destroy+0x164/0x1b0 security/apparmor/lib.c:509, CPU#0: syz.0.17/5541
Modules linked in:
CPU: 0 UID: 0 PID: 5541 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:aa_policy_destroy+0x16b/0x1b0 security/apparmor/lib.c:509
Code: 85 ed 7e 4d e8 96 bc 37 fd 5b 41 5c 41 5e 41 5f 5d e9 19 27 4e 07 cc e8 83 bc 37 fd 48 8d 3d 0c f0 d3 0b 48 c7 c6 a4 eb 38 8e <67> 48 0f b9 3a e9 04 ff ff ff e8 66 bc 37 fd 48 8d 3d ff ef d3 0b
RSP: 0018:ffffc9000345eaa0 EFLAGS: 00010293
RAX: ffffffff848f530d RBX: ffff88803f734800 RCX: ffff88801af2a580
RDX: 0000000000000000 RSI: ffffffff8e38eba4 RDI: ffffffff90634320
RBP: 0000000000000000 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: dffffc0000000000 R11: fffffbfff1d95913 R12: dead000000000122
R13: ffff88803f734800 R14: ffff88803f734828 R15: dffffc0000000000
FS:  00007f5f6a1836c0(0000) GS:ffff88808c519000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d02407b048 CR3: 0000000012aa9000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 aa_free_profile+0x9d/0x9f0 security/apparmor/policy.c:334
 aa_alloc_profile+0x1e4/0x3e0 security/apparmor/policy.c:416
 unpack_profile security/apparmor/policy_unpack.c:1153 [inline]
 aa_unpack+0x17db/0x7430 security/apparmor/policy_unpack.c:1748
 aa_replace_profiles+0x226/0x2a20 security/apparmor/policy.c:1183
 policy_update+0x234/0x4a0 security/apparmor/apparmorfs.c:505
 profile_load+0x1cb/0x320 security/apparmor/apparmorfs.c:522
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5f6939e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5f6a183028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5f69625fa0 RCX: 00007f5f6939e0d9
RDX: 0000000000000041 RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007f5f6a183090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f5f69626038 R14: 00007f5f69625fa0 R15: 00007ffe23725c18

Reported-by: syzbot+faed97c4ed43bfe7fee5@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=faed97c4ed43bfe7fee5
Fixes: fe6bb31f590c9 ("apparmor: split out shared policy_XXX fns to lib")
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
index acf7f5189beca79e7ee575fbd88f5bc30e75e0ed..5d53c15e46a9eb855eb61d18a566d78a461b32ea 100644 (file)
--- a/security/apparmor/lib.c
+++ b/security/apparmor/lib.c
@@ -480,6 +480,8 @@ bool aa_policy_init(struct aa_policy *policy, const char *prefix,
        char *hname;
        size_t hname_sz;
 
+       INIT_LIST_HEAD(&policy->list);
+       INIT_LIST_HEAD(&policy->profiles);
        hname_sz = (prefix ? strlen(prefix) + 2 : 0) + strlen(name) + 1;
        /* freed by policy_free */
        hname = aa_str_alloc(hname_sz, gfp);
@@ -492,8 +494,6 @@ bool aa_policy_init(struct aa_policy *policy, const char *prefix,
        policy->hname = hname;
        /* base.name is a substring of fqname */
        policy->name = basename(policy->hname);
-       INIT_LIST_HEAD(&policy->list);
-       INIT_LIST_HEAD(&policy->profiles);
 
        return true;
 }