From e14ea3f5c37475e12a3b7fb7bd3165b0a4e77c51 Mon Sep 17 00:00:00 2001 From: Csaba Henk Date: Wed, 5 Jul 2017 17:48:37 +0200 Subject: 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 Reviewed-on: https://review.gluster.org/17706 Smoke: Gluster Build System Reviewed-by: Niels de Vos Reviewed-by: Amar Tumballi CentOS-regression: Gluster Build System --- xlators/protocol/server/src/server-helpers.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) (limited to 'xlators/protocol/server/src/server-helpers.c') diff --git a/xlators/protocol/server/src/server-helpers.c b/xlators/protocol/server/src/server-helpers.c index 37f7bca47f0..09e0012d70a 100644 --- a/xlators/protocol/server/src/server-helpers.c +++ b/xlators/protocol/server/src/server-helpers.c @@ -19,7 +19,6 @@ #include #include -#include #include "compound-fop-utils.h" /* based on nfs_fix_aux_groups() */ @@ -30,10 +29,10 @@ gid_resolve (server_conf_t *conf, call_stack_t *root) struct passwd mypw; char mystrs[1024]; struct passwd *result; - gid_t mygroups[GF_MAX_AUX_GROUPS]; + gid_t *mygroups; gid_list_t gl; const gid_list_t *agl; - int ngroups, i; + int ngroups; agl = gid_cache_lookup (&conf->gid_cache, root->uid, 0, 0); if (agl) { @@ -58,9 +57,8 @@ gid_resolve (server_conf_t *conf, call_stack_t *root) gf_msg_trace ("gid-cache", 0, "mapped %u => %s", root->uid, result->pw_name); - ngroups = GF_MAX_AUX_GROUPS; - ret = getgrouplist (result->pw_name, root->gid, mygroups, &ngroups); - if (ret == -1) { + ngroups = gf_getgrouplist (result->pw_name, root->gid, &mygroups); + if (ngroups == -1) { gf_msg ("gid-cache", GF_LOG_ERROR, 0, PS_MSG_MAPPING_ERROR, "could not map %s to group list (%d gids)", result->pw_name, root->ngrps); @@ -84,8 +82,10 @@ fill_groups: if (gl.gl_list) memcpy (gl.gl_list, mygroups, sizeof(gid_t) * root->ngrps); - else + else { + GF_FREE (mygroups); return -1; + } } if (root->ngrps == 0) { @@ -93,14 +93,7 @@ fill_groups: goto out; } - if (call_stack_alloc_groups (root, root->ngrps) != 0) { - ret = -1; - goto out; - } - - /* finally fill the groups from the */ - for (i = 0; i < root->ngrps; ++i) - root->groups[i] = gl.gl_list[i]; + call_stack_set_groups (root, root->ngrps, mygroups); out: if (agl) { -- cgit