From: Tuomas Tynkkynen <tuomas.tynkkynen@xxxxxx> commit 7ea862048317aa76d0f22334202779a25530980c upstream. syzbot reports a warning: precision 33020 too large WARNING: CPU: 0 PID: 9618 at lib/vsprintf.c:2471 set_precision+0x150/0x180 lib/vsprintf.c:2471 vsnprintf+0xa7b/0x19a0 lib/vsprintf.c:2547 kvasprintf+0xb2/0x170 lib/kasprintf.c:22 kasprintf+0xbb/0xf0 lib/kasprintf.c:59 hwsim_del_radio_nl+0x63a/0x7e0 drivers/net/wireless/mac80211_hwsim.c:3625 genl_family_rcv_msg_doit net/netlink/genetlink.c:672 [inline] ... entry_SYSCALL_64_after_hwframe+0x49/0xbe Thus it seems that kasprintf() with "%.*s" format can not be used for duplicating a string with arbitrary length. Replace it with kstrndup(). Note that later this string is limited to NL80211_WIPHY_NAME_MAXLEN == 64, but the code is simpler this way. Reported-by: syzbot+6693adf1698864d21734@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: syzbot+a4aee3f42d7584d76761@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxx Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@xxxxxx> Link: https://lore.kernel.org/r/20200410123257.14559-1-tuomas.tynkkynen@xxxxxx [johannes: add note about length limit] Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/wireless/mac80211_hwsim.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/net/wireless/mac80211_hwsim.c +++ b/drivers/net/wireless/mac80211_hwsim.c @@ -3600,9 +3600,9 @@ static int hwsim_new_radio_nl(struct sk_ } if (info->attrs[HWSIM_ATTR_RADIO_NAME]) { - hwname = kasprintf(GFP_KERNEL, "%.*s", - nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]), - (char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME])); + hwname = kstrndup((char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]), + nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]), + GFP_KERNEL); if (!hwname) return -ENOMEM; param.hwname = hwname; @@ -3622,9 +3622,9 @@ static int hwsim_del_radio_nl(struct sk_ if (info->attrs[HWSIM_ATTR_RADIO_ID]) { idx = nla_get_u32(info->attrs[HWSIM_ATTR_RADIO_ID]); } else if (info->attrs[HWSIM_ATTR_RADIO_NAME]) { - hwname = kasprintf(GFP_KERNEL, "%.*s", - nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]), - (char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME])); + hwname = kstrndup((char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]), + nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]), + GFP_KERNEL); if (!hwname) return -ENOMEM; } else
