On Thu, Nov 30 2017, Thiago Rafael Becker wrote:
> The responsibility for calling groups_sort is now on the caller
> of set_groups.
>
> Signed-off-by: Thiago Rafael Becker <thiago.bec...@gmail.com>
> ---
> kernel/groups.c | 1 +
> kernel/uid16.c | 1 +
> net/sunrpc/svcauth_unix.c | 7 +++++++
> 3 files changed, 9 insertions(+)
>
> diff --git a/kernel/groups.c b/kernel/groups.c
> index 4c9c9ed..17073a9 100644
> --- a/kernel/groups.c
> +++ b/kernel/groups.c
> @@ -208,6 +208,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user
> *, grouplist)
> return retval;
> }
>
> + groups_sort(group_info);
> retval = set_current_groups(group_info);
> put_group_info(group_info);
>
> diff --git a/kernel/uid16.c b/kernel/uid16.c
> index ce74a49..ef1da2a 100644
> --- a/kernel/uid16.c
> +++ b/kernel/uid16.c
> @@ -192,6 +192,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t
> __user *, grouplist)
> return retval;
> }
>
> + groups_sort(group_info);
> retval = set_current_groups(group_info);
> put_group_info(group_info);
>
> diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
> index f81eaa8..91e3d34 100644
> --- a/net/sunrpc/svcauth_unix.c
> +++ b/net/sunrpc/svcauth_unix.c
> @@ -20,6 +20,7 @@
>
>
> #include "netns.h"
> +void groups_sort(struct group_info *group_info);
>
> /*
> * AUTHUNIX and AUTHNULL credentials are both handled here.
> @@ -520,6 +521,12 @@ static int unix_gid_parse(struct cache_detail *cd,
> ug.gi->gid[i] = kgid;
> }
>
> + /* Sort the groups before inserting this entry
> + * into the cache to avoid future corrutpions
> + * by multiple simultaneous attempts to sort this
> + * entry.
> + */
> + groups_sort(ug.gi);
> ugp = unix_gid_lookup(cd, uid);
> if (ugp) {
> struct cache_head *ch;I think you need to add groups_sort() in a few more places. Almost anywhere that calls groups_alloc() should be considered. net/sunrpc/svcauth_unix.c, net/sunrpc/auth_gss/svcauth_gss.c, fs/nfsd/auth.c definitely need it. I wonder if there is a more robust way to fix this. Maybe: groups_alloc() could initialize ->usage to -1 groups_sort() to require it be -1, and change it to 1 get_group_info() complains if ->usage is -1 ??? or something. Maybe it could be done with types. 'struct group_info' could be declared with ngroups and gid[] as const. 'struct group_info_unsorted' could be the same structure but without the 'const'. Then groups_sort() takes a 'struct group_info_unsorted *' and returns a 'struct group_info *'... Thanks, NeilBrown
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