2022-04-28 09:28:19

by Xin Xiong

Subject: [PATCH] apparmor: fix reference count leak in aa_pivotroot()

The aa_pivotroot() function has a reference counting bug in a specific
path. When aa_replace_current_label() returns on success, the function
forgets to decrement the reference count of “target”, which is
increased earlier by build_pivotroot(), causing a reference leak.

Fix it by decreasing the refcount of “target” in that path.

Fixes: 2ea3ffb7782a ("apparmor: add mount mediation")
Co-developed-by: Xiyu Yang <[email protected]>
Signed-off-by: Xiyu Yang <[email protected]>
Co-developed-by: Xin Tan <[email protected]>
Signed-off-by: Xin Tan <[email protected]>
Signed-off-by: Xin Xiong <[email protected]>
---
security/apparmor/mount.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
index aa6fcfde3051..d0b19ab9137d 100644
--- a/security/apparmor/mount.c
+++ b/security/apparmor/mount.c
@@ -718,6 +718,7 @@ int aa_pivotroot(struct aa_label *label, const struct path *old_path,
aa_put_label(target);
goto out;
}
+ aa_put_label(target);
} else
/* already audited error */
error = PTR_ERR(target);
--
2.25.1

2022-05-20 17:11:28

by John Johansen

Subject: Re: [PATCH] apparmor: fix reference count leak in aa_pivotroot()

On 4/27/22 20:39, Xin Xiong wrote:
> The aa_pivotroot() function has a reference counting bug in a specific
> path. When aa_replace_current_label() returns on success, the function
> forgets to decrement the reference count of “target”, which is
> increased earlier by build_pivotroot(), causing a reference leak.
>
> Fix it by decreasing the refcount of “target” in that path.
>
> Fixes: 2ea3ffb7782a ("apparmor: add mount mediation")
> Co-developed-by: Xiyu Yang <[email protected]>
> Signed-off-by: Xiyu Yang <[email protected]>
> Co-developed-by: Xin Tan <[email protected]>
> Signed-off-by: Xin Tan <[email protected]>
> Signed-off-by: Xin Xiong <[email protected]>

thanks I have pulled it into my tree

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


> ---
> security/apparmor/mount.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
> index aa6fcfde3051..d0b19ab9137d 100644
> --- a/security/apparmor/mount.c
> +++ b/security/apparmor/mount.c
> @@ -718,6 +718,7 @@ int aa_pivotroot(struct aa_label *label, const struct path *old_path,
> aa_put_label(target);
> goto out;
> }
> + aa_put_label(target);
> } else
> /* already audited error */
> error = PTR_ERR(target);