lkml.org 
[lkml]   [2022]   [Aug]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.19 0763/1157] kernfs: fix potential NULL dereference in __kernfs_remove
    Date
    From: Yushan Zhou <katrinzhou@tencent.com>

    [ Upstream commit 72b5d5aef246a0387cefa23121dd90901c7a691a ]

    When lockdep is enabled, lockdep_assert_held_write would
    cause potential NULL pointer dereference.

    Fix the following smatch warnings:

    fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before check 'kn' (see line 1346)

    Fixes: 393c3714081a ("kernfs: switch global kernfs_rwsem lock to per-fs lock")
    Signed-off-by: Yushan Zhou <katrinzhou@tencent.com>
    Link: https://lore.kernel.org/r/20220630082512.3482581-1-zys.zljxml@gmail.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/kernfs/dir.c | 7 +++++--
    1 file changed, 5 insertions(+), 2 deletions(-)

    diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
    index 6eca72cfa1f2..1cc88ba6de90 100644
    --- a/fs/kernfs/dir.c
    +++ b/fs/kernfs/dir.c
    @@ -1343,14 +1343,17 @@ static void __kernfs_remove(struct kernfs_node *kn)
    {
    struct kernfs_node *pos;

    + /* Short-circuit if non-root @kn has already finished removal. */
    + if (!kn)
    + return;
    +
    lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);

    /*
    - * Short-circuit if non-root @kn has already finished removal.
    * This is for kernfs_remove_self() which plays with active ref
    * after removal.
    */
    - if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb)))
    + if (kn->parent && RB_EMPTY_NODE(&kn->rb))
    return;

    pr_debug("kernfs %s: removing\n", kn->name);
    --
    2.35.1


    \
     
     \ /
      Last update: 2022-08-16 06:45    [W:2.653 / U:0.060 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site