From 46443eaddebd84c51940857b11787229be169dec Mon Sep 17 00:00:00 2001 From: Hidayath Khan Date: Thu, 30 Jul 2026 16:22:16 +0200 Subject: [PATCH] s390/qeth: validate user buffer length in SNMP and ARP query ioctls commit d141f087b1af656f055d7c5793a3e87817ba0bbe upstream. qeth_snmp_command() and qeth_l3_arp_query() allocate a buffer sized by a user-supplied length (udata_len) without checking a lower bound, then set udata_offset to a fixed non-zero value and pass both to a reply callback. The callback bounds-checks the copy with if ((udata_len - udata_offset) < len) Both fields are u32, so a udata_len smaller than udata_offset makes the subtraction wrap and the check pass, and the following memcpy() writes past the allocation. A udata_len of 0 also yields ZERO_SIZE_PTR from kzalloc(), which the existing NULL check does not catch. Reject buffers smaller than udata_offset before allocating, so the callback subtraction can no longer underflow. Fixes: 4a71df50047f ("qeth: new qeth device driver") Cc: stable@vger.kernel.org Reviewed-by: Alexandra Winter Signed-off-by: Hidayath Khan Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260730142216.218309-1-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/s390/net/qeth_core_main.c | 3 +++ drivers/s390/net/qeth_l3_main.c | 5 +++++ 2 files changed, 8 insertions(+) diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 9531db0660e9..dbde0a2a9e15 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -4674,6 +4674,9 @@ static int qeth_snmp_command(struct qeth_card *card, char __user *udata) if (req_len > QETH_BUFSIZE) return -EINVAL; + if (qinfo.udata_len < sizeof(struct qeth_snmp_ureq_hdr)) + return -EINVAL; + iob = qeth_get_adapter_cmd(card, IPA_SETADP_SET_SNMP_CONTROL, req_len); if (!iob) return -ENOMEM; diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index 83af6c6a9e21..1a3045811b25 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -1415,6 +1415,11 @@ static int qeth_l3_arp_query(struct qeth_card *card, char __user *udata) rc = -EFAULT; goto out; } + + if (qinfo.udata_len < QETH_QARP_ENTRIES_OFFSET) { + rc = -EINVAL; + goto out; + } qinfo.udata = kzalloc(qinfo.udata_len, GFP_KERNEL); if (!qinfo.udata) { rc = -ENOMEM;