CVE-2024-35949 — btrfs: make sure that WRITTEN is set on all metadata blocks

Affected: Linux

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

btrfs: make sure that WRITTEN is set on all metadata blocks

We previously would call btrfs_check_leaf() if we had the check integrity code enabled, which meant that we could only run the extended leaf checks if we had WRITTEN set on the header flags.

This leaves a gap in our checking, because we could end up with corruption on disk where WRITTEN isn't set on the leaf, and then the extended leaf checks don't get run which we rely on to validate all of the item pointers to make sure we don't access memory outside of the extent buffer.

However, since 732fab95abe2 ("btrfs: check-integrity: remove CONFIG_BTRFS_FS_CHECK_INTEGRITY option") we no longer call btrfs_check_leaf() from btrfs_mark_buffer_dirty(), which means we only ever call it on blocks that are being written out, and thus have WRITTEN set, or that are being read in, which should have WRITTEN set.

Add checks to make sure we have WRITTEN set appropriately, and then make sure __btrfs_check_leaf() always does the item checking. This will protect us from file systems that have been corrupted and no longer have WRITTEN set on some of the blocks.

This was hit on a crafted image tweaking the WRITTEN bit and reported by KASAN as out-of-bound access in the eb accessors. The example is a dir item at the end of an eb.

[2.042] BTRFS warning (device loop1): bad eb member start: ptr 0x3fff start 30572544 member offset 16410 size 2 [2.040] general protect…

USN-6949-1 — linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-nvidia, linux-nvidia-6.8 vulnerabilities

Affected: Ubuntu:22.04:LTS: linux-nvidia-6.8, Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-aws, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-gke, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-nvidia

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; - ARM64 architecture; - M68K architecture; - OpenRISC architecture; - PowerPC architecture; - RISC-V architecture; - x86 architecture; - Block layer subsystem; - Accessibility subsystem; - Bluetooth drivers; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - DMA engine subsystem; - DPLL subsystem; - FireWire subsystem; - EFI core; - Qualcomm firmware drivers; - GPIO subsystem; - GPU drivers; - Microsoft Hyper-V drivers; - InfiniBand drivers; - IOMMU subsystem; - IRQ chip drivers; - Macintosh device drivers; - Multiple devices driver; - Media drivers; - EEPROM drivers; - MMC subsystem; - Network drivers; - STMicroelectronics network drivers; - Device tree and open firmware driver; - HiSilicon SoC PMU drivers; - PHY drivers; - Pin controllers subsystem; - Remote Processor subsystem; - S/390 drivers; - SCSI drivers; - SPI subsystem; - Media staging drivers; - Thermal drivers; - Userspace I/O drivers; - USB subsystem; - DesignWare USB3 driver; - ACRN Hypervisor Service Module driver; - Virtio drivers; - 9P distributed file system; - BTRFS file system; - eCrypt file system; - EROFS file system; - File systems infrastructure; - GF…

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CVE-2024-35949 — btrfs: make sure that WRITTEN is set on all metadata blocks

USN-6949-1 — linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-nvidia, linux-nvidia-6.8 vulnerabilities