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    Subject[PATCH AUTOSEL 5.6 154/606] apparmor: fix potential label refcnt leak in aa_change_profile
    Date
    From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

    commit a0b845ffa0d91855532b50fc040aeb2d8338dca4 upstream.

    aa_change_profile() invokes aa_get_current_label(), which returns
    a reference of the current task's label.

    According to the comment of aa_get_current_label(), the returned
    reference must be put with aa_put_label().
    However, when the original object pointed by "label" becomes
    unreachable because aa_change_profile() returns or a new object
    is assigned to "label", reference count increased by
    aa_get_current_label() is not decreased, causing a refcnt leak.

    Fix this by calling aa_put_label() before aa_change_profile() return
    and dropping unnecessary aa_get_current_label().

    Fixes: 9fcf78cca198 ("apparmor: update domain transitions that are subsets of confinement at nnp")
    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/domain.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
    index 6ceb74e0f789..a84ef030fbd7 100644
    --- a/security/apparmor/domain.c
    +++ b/security/apparmor/domain.c
    @@ -1328,6 +1328,7 @@ int aa_change_profile(const char *fqname, int flags)
    ctx->nnp = aa_get_label(label);

    if (!fqname || !*fqname) {
    + aa_put_label(label);
    AA_DEBUG("no profile name");
    return -EINVAL;
    }
    @@ -1346,8 +1347,6 @@ int aa_change_profile(const char *fqname, int flags)
    op = OP_CHANGE_PROFILE;
    }

    - label = aa_get_current_label();
    -
    if (*fqname == '&') {
    stack = true;
    /* don't have label_parse() do stacking */
    --
    2.25.1
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