lkml.org 
[lkml]   [2020]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 45/81] apparmor: Fix aa_label refcnt leak in policy_update
    Date
    From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

    commit c6b39f070722ea9963ffe756bfe94e89218c5e63 upstream.

    policy_update() invokes begin_current_label_crit_section(), which
    returns a reference of the updated aa_label object to "label" with
    increased refcount.

    When policy_update() returns, "label" becomes invalid, so the refcount
    should be decreased to keep refcount balanced.

    The reference counting issue happens in one exception handling path of
    policy_update(). When aa_may_manage_policy() returns not NULL, the
    refcnt increased by begin_current_label_crit_section() is not decreased,
    causing a refcnt leak.

    Fix this issue by jumping to "end_section" label when
    aa_may_manage_policy() returns not NULL.

    Fixes: 5ac8c355ae00 ("apparmor: allow introspecting the loaded policy pre internal transform")
    Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
    Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
    Signed-off-by: John Johansen <john.johansen@canonical.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    security/apparmor/apparmorfs.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/security/apparmor/apparmorfs.c
    +++ b/security/apparmor/apparmorfs.c
    @@ -424,7 +424,7 @@ static ssize_t policy_update(u32 mask, c
    */
    error = aa_may_manage_policy(label, ns, mask);
    if (error)
    - return error;
    + goto end_section;

    data = aa_simple_write_to_buffer(buf, size, size, pos);
    error = PTR_ERR(data);
    @@ -432,6 +432,7 @@ static ssize_t policy_update(u32 mask, c
    error = aa_replace_profiles(ns, label, mask, data);
    aa_put_loaddata(data);
    }
    +end_section:
    end_current_label_crit_section(label);

    return error;

    \
     
     \ /
      Last update: 2020-05-26 21:04    [W:4.291 / U:0.324 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site