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    Subject[PATCH 5.15 450/667] proc: fix dentry/inode overinstantiating under /proc/${pid}/net
    Date
    From: Alexey Dobriyan <adobriyan@gmail.com>

    [ Upstream commit 7055197705709c59b8ab77e6a5c7d46d61edd96e ]

    When a process exits, /proc/${pid}, and /proc/${pid}/net dentries are
    flushed. However some leaf dentries like /proc/${pid}/net/arp_cache
    aren't. That's because respective PDEs have proc_misc_d_revalidate() hook
    which returns 1 and leaves dentries/inodes in the LRU.

    Force revalidation/lookup on everything under /proc/${pid}/net by
    inheriting proc_net_dentry_ops.

    [akpm@linux-foundation.org: coding-style cleanups]
    Link: https://lkml.kernel.org/r/YjdVHgildbWO7diJ@localhost.localdomain
    Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)")
    Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
    Reported-by: hui li <juanfengpy@gmail.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/proc/generic.c | 3 +++
    fs/proc/proc_net.c | 3 +++
    2 files changed, 6 insertions(+)

    diff --git a/fs/proc/generic.c b/fs/proc/generic.c
    index 5b78739e60e4..d32f69aaaa36 100644
    --- a/fs/proc/generic.c
    +++ b/fs/proc/generic.c
    @@ -448,6 +448,9 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
    proc_set_user(ent, (*parent)->uid, (*parent)->gid);

    ent->proc_dops = &proc_misc_dentry_ops;
    + /* Revalidate everything under /proc/${pid}/net */
    + if ((*parent)->proc_dops == &proc_net_dentry_ops)
    + pde_force_lookup(ent);

    out:
    return ent;
    diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
    index 15c2e55d2ed2..123e3c9d8674 100644
    --- a/fs/proc/proc_net.c
    +++ b/fs/proc/proc_net.c
    @@ -363,6 +363,9 @@ static __net_init int proc_net_ns_init(struct net *net)

    proc_set_user(netd, uid, gid);

    + /* Seed dentry revalidation for /proc/${pid}/net */
    + pde_force_lookup(netd);
    +
    err = -EEXIST;
    net_statd = proc_net_mkdir(net, "stat", netd);
    if (!net_statd)
    --
    2.35.1


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