neigh: prevent overflowing params in /proc/sys/net/ipv4/neigh/

Without this patch, the fields app_solicit, gc_thresh1, gc_thresh2,
gc_thresh3, proxy_qlen, ucast_solicit, mcast_solicit could have
assumed negative values when setting large numbers.

Signed-off-by: Francesco Fusco <ffusco@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 7 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index b7de821f98df..9232c68941ab 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2767,6 +2767,7 @@ EXPORT_SYMBOL(neigh_app_ns);
 
 #ifdef CONFIG_SYSCTL
 static int zero;
+static int int_max = INT_MAX;
 static int unres_qlen_max = INT_MAX / SKB_TRUESIZE(ETH_FRAME_LEN);
 
 static int proc_unres_qlen(struct ctl_table *ctl, int write,
@@ -2819,19 +2820,25 @@ static struct neigh_sysctl_table {
                         .procname       = "mcast_solicit",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_UCAST_PROBE] = {
                         .procname       = "ucast_solicit",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_APP_PROBE] = {
                         .procname       = "app_solicit",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_RETRANS_TIME] = {
                         .procname       = "retrans_time",
@@ -2874,7 +2881,9 @@ static struct neigh_sysctl_table {
                         .procname       = "proxy_qlen",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_ANYCAST_DELAY] = {
                         .procname       = "anycast_delay",
@@ -2916,19 +2925,25 @@ static struct neigh_sysctl_table {
                         .procname       = "gc_thresh1",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_GC_THRESH2] = {
                         .procname       = "gc_thresh2",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 [NEIGH_VAR_GC_THRESH3] = {
                         .procname       = "gc_thresh3",
                         .maxlen         = sizeof(int),
                         .mode           = 0644,
-                        .proc_handler   = proc_dointvec,
+                        .extra1         = &zero,
+                        .extra2         = &int_max,
+                        .proc_handler   = proc_dointvec_minmax,
                 },
                 {},
         },