2023-11-27 17:59:56

by Fedor Pchelkin

Subject: [PATCH] apparmor: free the allocated pdb objects

policy_db objects are allocated with kzalloc() inside aa_alloc_pdb() and
are not cleared in the corresponding aa_free_pdb() function causing leak:

unreferenced object 0xffff88801f0a1400 (size 192):
comm "apparmor_parser", pid 1247, jiffies 4295122827 (age 2306.399s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81ddc612>] __kmem_cache_alloc_node+0x1e2/0x2d0
[<ffffffff81c47c55>] kmalloc_trace+0x25/0xc0
[<ffffffff83eb9a12>] aa_alloc_pdb+0x82/0x140
[<ffffffff83ec4077>] unpack_pdb+0xc7/0x2700
[<ffffffff83ec6b10>] unpack_profile+0x450/0x4960
[<ffffffff83ecc129>] aa_unpack+0x309/0x15e0
[<ffffffff83ebdb23>] aa_replace_profiles+0x213/0x33c0
[<ffffffff83e8d341>] policy_update+0x261/0x370
[<ffffffff83e8d66e>] profile_replace+0x20e/0x2a0
[<ffffffff81eadfaf>] vfs_write+0x2af/0xe00
[<ffffffff81eaf4c6>] ksys_write+0x126/0x250
[<ffffffff890fa0b6>] do_syscall_64+0x46/0xf0
[<ffffffff892000ea>] entry_SYSCALL_64_after_hwframe+0x6e/0x76

Free the pdbs inside aa_free_pdb(). While at it, rename the variable
representing an aa_policydb object to make the function more unified with
aa_pdb_free_kref() and aa_alloc_pdb().

Found by Linux Verification Center (linuxtesting.org).

Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
Signed-off-by: Fedor Pchelkin <[email protected]>
---
security/apparmor/policy.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index ed4c9803c8fa..957654d253dd 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -99,13 +99,14 @@ const char *const aa_profile_mode_names[] = {
};


-static void aa_free_pdb(struct aa_policydb *policy)
+static void aa_free_pdb(struct aa_policydb *pdb)
{
- if (policy) {
- aa_put_dfa(policy->dfa);
- if (policy->perms)
- kvfree(policy->perms);
- aa_free_str_table(&policy->trans);
+ if (pdb) {
+ aa_put_dfa(pdb->dfa);
+ if (pdb->perms)
+ kvfree(pdb->perms);
+ aa_free_str_table(&pdb->trans);
+ kfree(pdb);
}
}

--
2.34.1

2023-11-28 14:29:54

by John Johansen

Subject: Re: [PATCH] apparmor: free the allocated pdb objects

On 11/27/23 09:59, Fedor Pchelkin wrote:
> policy_db objects are allocated with kzalloc() inside aa_alloc_pdb() and
> are not cleared in the corresponding aa_free_pdb() function causing leak:
>
> unreferenced object 0xffff88801f0a1400 (size 192):
> comm "apparmor_parser", pid 1247, jiffies 4295122827 (age 2306.399s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<ffffffff81ddc612>] __kmem_cache_alloc_node+0x1e2/0x2d0
> [<ffffffff81c47c55>] kmalloc_trace+0x25/0xc0
> [<ffffffff83eb9a12>] aa_alloc_pdb+0x82/0x140
> [<ffffffff83ec4077>] unpack_pdb+0xc7/0x2700
> [<ffffffff83ec6b10>] unpack_profile+0x450/0x4960
> [<ffffffff83ecc129>] aa_unpack+0x309/0x15e0
> [<ffffffff83ebdb23>] aa_replace_profiles+0x213/0x33c0
> [<ffffffff83e8d341>] policy_update+0x261/0x370
> [<ffffffff83e8d66e>] profile_replace+0x20e/0x2a0
> [<ffffffff81eadfaf>] vfs_write+0x2af/0xe00
> [<ffffffff81eaf4c6>] ksys_write+0x126/0x250
> [<ffffffff890fa0b6>] do_syscall_64+0x46/0xf0
> [<ffffffff892000ea>] entry_SYSCALL_64_after_hwframe+0x6e/0x76
>
> Free the pdbs inside aa_free_pdb(). While at it, rename the variable
> representing an aa_policydb object to make the function more unified with
> aa_pdb_free_kref() and aa_alloc_pdb().
>
> Found by Linux Verification Center (linuxtesting.org).
>
> Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
> Signed-off-by: Fedor Pchelkin <[email protected]>

ouch, lgtm, I am going to pull this into my tree and throw some testing
on this asap

Acked-by: John Johansen <[email protected]>

> ---
> security/apparmor/policy.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
> index ed4c9803c8fa..957654d253dd 100644
> --- a/security/apparmor/policy.c
> +++ b/security/apparmor/policy.c
> @@ -99,13 +99,14 @@ const char *const aa_profile_mode_names[] = {
> };
>
>
> -static void aa_free_pdb(struct aa_policydb *policy)
> +static void aa_free_pdb(struct aa_policydb *pdb)
> {
> - if (policy) {
> - aa_put_dfa(policy->dfa);
> - if (policy->perms)
> - kvfree(policy->perms);
> - aa_free_str_table(&policy->trans);
> + if (pdb) {
> + aa_put_dfa(pdb->dfa);
> + if (pdb->perms)
> + kvfree(pdb->perms);
> + aa_free_str_table(&pdb->trans);
> + kfree(pdb);
> }
> }
>