CVE-2025-71067 — ntfs: set dummy blocksize to read boot_block when mounting

Affected: Linux

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

ntfs: set dummy blocksize to read boot_block when mounting

When mounting, sb->s_blocksize is used to read the boot_block without being defined or validated. Set a dummy blocksize before attempting to read the boot_block.

The issue can be triggered with the following syz reproducer:

mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0) r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0) ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000) mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00', &(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0) syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0)

Here, the ioctl sets the bdev block size to 16384. During mount, get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)), but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves sb->s_blocksize at zero.

Later, ntfs_init_from_boot() attempts to read the boot_block while sb->s_blocksize is still zero, which triggers the bug.

[almaz.alexandrovich@paragon-software.com: changed comment style, added return value handling]

USN-8177-1 — linux, linux-realtime vulnerabilities

Affected: Ubuntu:25.10: linux, Ubuntu:25.10: linux-realtime

Josh Eads, Kristoffer Janke, Eduardo Vela Nava, Tavis Ormandy, and Matteo Rizzo discovered that some AMD Zen processors did not properly verify the signature of CPU microcode. This flaw is known as EntrySign. A privileged attacker could possibly use this issue to cause load malicious CPU microcode causing loss of integrity and confidentiality. (CVE-2024-36347)

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: - MIPS architecture; - PowerPC architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Cryptographic API; - ACPI drivers; - Ublk userspace block driver; - Bluetooth drivers; - Character device driver; - TPM device driver; - Clock framework and drivers; - GPU drivers; - Hardware monitoring drivers; - Intel Trace Hub HW tracing drivers; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - Ethernet team driver; - PA-RISC drivers; - Chrome hardware platform drivers; - x86 platform drivers; - SCSI subsystem; - SPI subsystem; - TCM subsystem; - Freescale USB OTG Transceiver Driver; - USB Type-C Connector System Software Interface driver; - Watchdog drivers; - BTRFS file sy…

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CVE-2025-71067 — ntfs: set dummy blocksize to read boot_block when mounting

USN-8177-1 — linux, linux-realtime vulnerabilities