On Mon, May 07, 2018 at 04:59:09PM -0400, Waiman Long wrote:
> A user can write arbitrary integer values to msgmni and shmmni sysctl
> parameters without getting error, but the actual limit is really
> IPCMNI (32k). This can mislead users as they think they can get a
> value that is not real.
>
> The right limits are now set for msgmni and shmmni so that the users
> will become aware if they set a value outside of the acceptable range.
>
> Signed-off-by: Waiman Long <long...@redhat.com>
> ---
> ipc/ipc_sysctl.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
> index 8ad93c2..f87cb29 100644
> --- a/ipc/ipc_sysctl.c
> +++ b/ipc/ipc_sysctl.c
> @@ -99,6 +99,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table,
> int write,
> static int zero;
> static int one = 1;
> static int int_max = INT_MAX;
> +static int ipc_mni = IPCMNI;
>
> static struct ctl_table ipc_kern_table[] = {
> {
> @@ -120,7 +121,9 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table,
> int write,
> .data = &init_ipc_ns.shm_ctlmni,
> .maxlen = sizeof(init_ipc_ns.shm_ctlmni),
> .mode = 0644,
> - .proc_handler = proc_ipc_dointvec,
> + .proc_handler = proc_ipc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &ipc_mni,
> },
> {
> .procname = "shm_rmid_forced",
> @@ -147,7 +150,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table,
> int write,
> .mode = 0644,
> .proc_handler = proc_ipc_dointvec_minmax,
> .extra1 = &zero,
> - .extra2 = &int_max,
> + .extra2 = &ipc_mni,
> },
> {
> .procname = "auto_msgmni",
> --
> 1.8.3.1
It seems negative values are not allowed, if true then having
a caller to use proc_douintvec_minmax() would help with ensuring
no invalid negative input values are used as well.
Luis
