Affected: Linux

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

tcp: Correct signedness in skb remaining space calculation

Syzkaller reported a bug [1] where sk->sk_forward_alloc can overflow.

When we send data, if an skb exists at the tail of the write queue, the kernel will attempt to append the new data to that skb. However, the code that checks for available space in the skb is flawed: ''' copy = size_goal - skb->len '''

The types of the variables involved are: ''' copy: ssize_t (s64 on 64-bit systems) size_goal: int skb->len: unsigned int '''

Due to C's type promotion rules, the signed size_goal is converted to an unsigned int to match skb->len before the subtraction. The result is an unsigned int.

When this unsigned int result is then assigned to the s64 copy variable, it is zero-extended, preserving its non-negative value. Consequently, copy is always >= 0.

Assume we are sending 2GB of data and size_goal has been adjusted to a value smaller than skb->len. The subtraction will result in copy holding a very large positive integer. In the subsequent logic, this large value is used to update sk->sk_forward_alloc, which can easily cause it to overflow.

The syzkaller reproducer uses TCP_REPAIR to reliably create this condition. However, this can also occur in real-world scenarios. The tcp_bound_to_half_wnd() function can also reduce size_goal to a small value. This would cause the subsequent tcp_wmem_schedule() to set sk->sk_forward_alloc to a value close to INT…

Affected: Ubuntu:24.04:LTS: linux-hwe-6.14

It was discovered that improper initialization of CPU cache memory could allow a local attacker with hypervisor access to overwrite SEV-SNP guest memory resulting in loss of data integrity. (CVE-2024-36331)

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: - ARM64 architecture; - PowerPC architecture; - S390 architecture; - x86 architecture; - Network block device driver; - Character device driver; - Clock framework and drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - DMA engine subsystem; - EDAC drivers; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - IIO subsystem; - IIO ADC drivers; - InfiniBand drivers; - Input Device core drivers; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - PCI subsystem; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - Power supply drivers; - Powercap sysfs driver; - Voltage and Current Regulator drivers; - S/390 drivers; - ASPEED SoC drivers; - SPI subsystem; - small TFT LCD display modules; - Media staging drivers; - USB Gadget drivers; - vDPA drivers; - VFIO drivers; - Framebuffer layer; - Xen hypervisor drivers; - BTRFS file system; - Ceph distributed file sy…