Re: [apparmor] [PATCH] apparmor: Fix memory leak in unpack_profile()

[John Johansen]

On 1/4/24 18:01, Gaosheng Cui wrote:

The aa_put_pdb(rules->file) should be called when rules->file is
reassigned, otherwise there may be a memory leak.

This was found via kmemleak:

unreferenced object 0xffff986c17056600 (size 192):
   comm "apparmor_parser", pid 875, jiffies 4294893488
   hex dump (first 32 bytes):
     00 00 00 00 00 00 00 00 00 89 14 04 6c 98 ff ff  ............l...
     00 00 8c 11 6c 98 ff ff bc 0c 00 00 00 00 00 00  ....l...........
   backtrace (crc e28c80c4):
     [<ffffffffba25087f>] kmemleak_alloc+0x4f/0x90
     [<ffffffffb95ecd42>] kmalloc_trace+0x2d2/0x340
     [<ffffffffb98a7b3d>] aa_alloc_pdb+0x4d/0x90
     [<ffffffffb98ab3b8>] unpack_pdb+0x48/0x660
     [<ffffffffb98ac073>] unpack_profile+0x693/0x1090
     [<ffffffffb98acf5a>] aa_unpack+0x10a/0x6e0
     [<ffffffffb98a93e3>] aa_replace_profiles+0xa3/0x1210
     [<ffffffffb989a183>] policy_update+0x163/0x2a0
     [<ffffffffb989a381>] profile_replace+0xb1/0x130
     [<ffffffffb966cb64>] vfs_write+0xd4/0x3d0
     [<ffffffffb966d05b>] ksys_write+0x6b/0xf0
     [<ffffffffb966d10e>] __x64_sys_write+0x1e/0x30
     [<ffffffffba242316>] do_syscall_64+0x76/0x120
     [<ffffffffba4000e5>] entry_SYSCALL_64_after_hwframe+0x6c/0x74

So add aa_put_pdb(rules->file) to fix it when rules->file is reassigned.

Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
Signed-off-by: Gaosheng Cui <cuigaoshe...@huawei.com>

yep, thanks. I have pulled this into the apparmor tree

Acked-by: John Johansen <john.johan...@canonical.com>

---
  security/apparmor/policy_unpack.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/security/apparmor/policy_unpack.c 
b/security/apparmor/policy_unpack.c
index 47ec097d6741..16afe992a724 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -1022,8 +1022,10 @@ static struct aa_profile *unpack_profile(struct aa_ext 
*e, char **ns_name)
                }
        } else if (rules->policy->dfa &&
                   rules->policy->start[AA_CLASS_FILE]) {
+               aa_put_pdb(rules->file);
                rules->file = aa_get_pdb(rules->policy);
        } else {
+               aa_put_pdb(rules->file);
                rules->file = aa_get_pdb(nullpdb);
        }
        error = -EPROTO;