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CVE-2024-49949 — net: avoid potential underflow in qdisc_pkt_len_init() with UFO

Affected: Linux, Siemens RUGGEDCOM RST2428P, Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family, Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family, Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

In the Linux kernel, the following vulnerability has been resolved:

net: avoid potential underflow in qdisc_pkt_len_init() with UFO

After commit 7c6d2ecbda83 ("net: be more gentle about silly gso requests coming from user") virtio_net_hdr_to_skb() had sanity check to detect malicious attempts from user space to cook a bad GSO packet.

Then commit cf9acc90c80ec ("net: virtio_net_hdr_to_skb: count transport header in UFO") while fixing one issue, allowed user space to cook a GSO packet with the following characteristic :

IPv4 SKB_GSO_UDP, gso_size=3, skb->len = 28.

When this packet arrives in qdisc_pkt_len_init(), we end up with hdr_len = 28 (IPv4 header + UDP header), matching skb->len

Then the following sets gso_segs to 0 :

gso_segs = DIV_ROUND_UP(skb->len - hdr_len, shinfo->gso_size);

Then later we set qdisc_skb_cb(skb)->pkt_len to back to zero :/

qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;

This leads to the following crash in fq_codel [1]

qdisc_pkt_len_init() is best effort, we only want an estimation of the bytes sent on the wire, not crashing the kernel.

This patch is fixing this particular issue, a following one adds more sanity checks for another potential bug.

[1] [ 70.724101] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 70.724561] #PF: supervisor read access in kernel mode [ 70.724561] #PF: error_code(0x0000) - not-present page [ 70.724561] PGD 10ac61067 P4D 10ac61067 PUD 107ee2067 PMD 0 […

USN-7166-1 — linux, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-kvm, linux-lowlatency, linux…

Affected: Ubuntu:20.04:LTS: linux-gcp-5.15, Ubuntu:20.04:LTS: linux-ibm-5.15, Ubuntu:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:20.04:LTS: linux-oracle-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-gcp, Ubuntu:22.04:LTS: linux-gke, Ubuntu:22.04:LTS: linux-gkeop, Ubuntu:22.04:LTS: linux-ibm, Ubuntu:22.04:LTS: linux-kvm and 4 more

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM32 architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - ACPI drivers; - Drivers core; - ATA over ethernet (AOE) driver; - TPM device driver; - Clock framework and drivers; - Buffer Sharing and Synchronization framework; - EFI core; - GPIO subsystem; - GPU drivers; - HID subsystem; - I2C subsystem; - InfiniBand drivers; - Input Device core drivers; - Mailbox framework; - Media drivers; - Ethernet bonding driver; - Network drivers; - Mellanox network drivers; - Microsoft Azure Network Adapter (MANA) driver; - STMicroelectronics network drivers; - NTB driver; - Virtio pmem driver; - PCI subsystem; - x86 platform drivers; - S/390 drivers; - SCSI subsystem; - SPI subsystem; - Thermal drivers; - USB Device Class drivers; - USB Type-C Port Controller Manager driver; - VFIO drivers; - Virtio Host (VHOST) subsystem; - Framebuffer layer; - 9P distributed file system; - BTRFS file system; - Ceph distributed file system; - File systems infrastructure; - Ext4 file system; - F2FS file system; - GFS2 file system; - JFS file system; - Network file system (NFS) client; - Network file system (NFS) server daemon; - NILFS2 file system; - Network file system (NFS)…