groups_alloc() can return NULL for 'group_info', also group_search() already considers about NULL for 'group_info', so can assume the caller has right to use all related extern functions when 'group_info' is NULL.
For groups_free(), need check NULL to match groups_alloc(), just like kmalloc/free(). For set_groups(), can allow the caller to set NULL parameter to new 'cred'. For system call getgroups(), if 'cred->group_info' is NULL, need return the related error code (no related data), also need change the related man page ("man 2 getgroups") to complete the return value. Signed-off-by: Chen Gang <gang.c...@asianux.com> --- kernel/groups.c | 14 +++++++++++--- 1 files changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/groups.c b/kernel/groups.c index 6b2588d..a21a4ce 100644 --- a/kernel/groups.c +++ b/kernel/groups.c @@ -52,6 +52,9 @@ EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info *group_info) { + if (!group_info) + return; + if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) @@ -163,9 +166,12 @@ int groups_search(const struct group_info *group_info, kgid_t grp) */ int set_groups(struct cred *new, struct group_info *group_info) { - put_group_info(new->group_info); - groups_sort(group_info); - get_group_info(group_info); + if (new->group_info) + put_group_info(new->group_info); + if (group_info) { + groups_sort(group_info); + get_group_info(group_info); + } new->group_info = group_info; return 0; } @@ -206,6 +212,8 @@ SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) if (gidsetsize < 0) return -EINVAL; + if (!cred->group_info) + return -ENODATA; /* no need to grab task_lock here; it cannot change */ i = cred->group_info->ngroups; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/