The TVLV for the gw_bandwidth stores everything as u32. But the gw_bandwidth reads the signed long which limits the maximum value to (2 ** 31 - 1) on systems with 4 byte long. Also the input value is always converted from either Mibit/s or Kibit/s to 100Kibit/s. This reduces the values even further when the user sets it via the default unit Kibit/s. It may even cause an integer overflow and end up with a value the user never intended.
Instead read the values as u64, check for possible overflows, do the unit adjustments and then reduce the size to u32.
Signed-off-by: Sven Eckelmann sven@narfation.org --- v3: * replaced do_div with faster div_u64 v2: * rebased on current master * add missing header linux/errno.h
net/batman-adv/gateway_common.c | 49 +++++++++++++++++++++++++++++++++++------ 1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/net/batman-adv/gateway_common.c b/net/batman-adv/gateway_common.c index 6b930a6..0cb5e6b 100644 --- a/net/batman-adv/gateway_common.c +++ b/net/batman-adv/gateway_common.c @@ -22,6 +22,7 @@ #include <linux/errno.h> #include <linux/byteorder/generic.h> #include <linux/kernel.h> +#include <linux/math64.h> #include <linux/netdevice.h> #include <linux/stddef.h> #include <linux/string.h> @@ -44,7 +45,7 @@ static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff, { enum batadv_bandwidth_units bw_unit_type = BATADV_BW_UNIT_KBIT; char *slash_ptr, *tmp_ptr; - long ldown, lup; + u64 ldown, lup; int ret;
slash_ptr = strchr(buff, '/'); @@ -62,7 +63,7 @@ static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff, *tmp_ptr = '\0'; }
- ret = kstrtol(buff, 10, &ldown); + ret = kstrtou64(buff, 10, &ldown); if (ret) { batadv_err(net_dev, "Download speed of gateway mode invalid: %s\n", @@ -72,14 +73,31 @@ static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff,
switch (bw_unit_type) { case BATADV_BW_UNIT_MBIT: - *down = ldown * 10; + /* prevent overflow */ + if (U64_MAX / 10 < ldown) { + batadv_err(net_dev, + "Download speed of gateway mode too large: %s\n", + buff); + return false; + } + + ldown *= 10; break; case BATADV_BW_UNIT_KBIT: default: - *down = ldown / 100; + ldown = div_u64(ldown, 100); break; }
+ if (U32_MAX < ldown) { + batadv_err(net_dev, + "Download speed of gateway mode too large: %s\n", + buff); + return false; + } + + *down = ldown; + /* we also got some upload info */ if (slash_ptr) { bw_unit_type = BATADV_BW_UNIT_KBIT; @@ -95,7 +113,7 @@ static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff, *tmp_ptr = '\0'; }
- ret = kstrtol(slash_ptr + 1, 10, &lup); + ret = kstrtou64(slash_ptr + 1, 10, &lup); if (ret) { batadv_err(net_dev, "Upload speed of gateway mode invalid: %s\n", @@ -105,13 +123,30 @@ static bool batadv_parse_gw_bandwidth(struct net_device *net_dev, char *buff,
switch (bw_unit_type) { case BATADV_BW_UNIT_MBIT: - *up = lup * 10; + /* prevent overflow */ + if (U64_MAX / 10 < lup) { + batadv_err(net_dev, + "Upload speed of gateway mode too large: %s\n", + slash_ptr + 1); + return false; + } + + lup *= 10; break; case BATADV_BW_UNIT_KBIT: default: - *up = lup / 100; + lup = div_u64(lup, 100); break; } + + if (U32_MAX < lup) { + batadv_err(net_dev, + "Upload speed of gateway mode too large: %s\n", + slash_ptr + 1); + return false; + } + + *up = lup; }
return true;