[Bugs] [Bug 1464327] glusterfs client crashes when reading large directory

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1464327



--- Comment #7 from Worker Ant <bugzilla-bot at gluster.org> ---
COMMIT: https://review.gluster.org/17706 committed in master by Jeff Darcy
(jeff at pl.atyp.us) 
------
commit e14ea3f5c37475e12a3b7fb7bd3165b0a4e77c51
Author: Csaba Henk <csaba at redhat.com>
Date:   Wed Jul 5 17:48:37 2017 +0200

    groups: don't allocate auxiliary gid list on stack

    When glusterfs wants to retrieve the list of auxiliary gids
    of a user, it typically allocates a sufficiently big gid_t
    array on stack and calls getgrouplist(3) with it. However,
    "sufficiently big" means to be of maximum supported gid list
    size, which in GlusterFS is GF_MAX_AUX_GROUPS = 64k.
    That means a 64k * sizeof(gid_t) = 256k allocation, which is
    big enough to overflow the stack in certain cases.

    A further observation is that stack allocation of the gid list
    brings no gain, as in all cases the content of the gid list
    eventually gets copied over to a heap allocated buffer.

    So we add a convenience wrapper of getgrouplist to libglusterfs
    called gf_getgrouplist which calls getgrouplist with a sufficiently
    big heap allocated buffer (it takes care of the allocation too).
    We are porting all the getgrouplist invocations to gf_getgrouplist
    and thus eliminate the huge stack allocation.

    BUG: 1464327
    Change-Id: Icea76d0d74dcf2f87d26cb299acc771ca3b32d2b
    Signed-off-by: Csaba Henk <csaba at redhat.com>
    Reviewed-on: https://review.gluster.org/17706
    Smoke: Gluster Build System <jenkins at build.gluster.org>
    Reviewed-by: Niels de Vos <ndevos at redhat.com>
    Reviewed-by: Amar Tumballi <amarts at redhat.com>
    CentOS-regression: Gluster Build System <jenkins at build.gluster.org>

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