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    Subject[PATCH 4.14 148/237] cifs: fix NULL dereference in match_prepath
    Date
    From: Ronnie Sahlberg <lsahlber@redhat.com>

    [ Upstream commit fe1292686333d1dadaf84091f585ee903b9ddb84 ]

    RHBZ: 1760879

    Fix an oops in match_prepath() by making sure that the prepath string is not
    NULL before we pass it into strcmp().

    This is similar to other checks we make for example in cifs_root_iget()

    Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
    Signed-off-by: Steve French <stfrench@microsoft.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/cifs/connect.c | 6 ++++--
    1 file changed, 4 insertions(+), 2 deletions(-)

    diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
    index f0b1279a7de66..6e5ecf70996a0 100644
    --- a/fs/cifs/connect.c
    +++ b/fs/cifs/connect.c
    @@ -3047,8 +3047,10 @@ match_prepath(struct super_block *sb, struct cifs_mnt_data *mnt_data)
    {
    struct cifs_sb_info *old = CIFS_SB(sb);
    struct cifs_sb_info *new = mnt_data->cifs_sb;
    - bool old_set = old->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH;
    - bool new_set = new->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH;
    + bool old_set = (old->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
    + old->prepath;
    + bool new_set = (new->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
    + new->prepath;

    if (old_set && new_set && !strcmp(new->prepath, old->prepath))
    return 1;
    --
    2.20.1


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