CVE-2024-35798 — btrfs: fix race in read_extent_buffer_pages()

Affected: Linux

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

btrfs: fix race in read_extent_buffer_pages()

There are reports from tree-checker that detects corrupted nodes, without any obvious pattern so possibly an overwrite in memory. After some debugging it turns out there's a race when reading an extent buffer the uptodate status can be missed.

To prevent concurrent reads for the same extent buffer, read_extent_buffer_pages() performs these checks:

/* (1) */ if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0;

/* (2) */ if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags)) goto done;

At this point, it seems safe to start the actual read operation. Once that completes, end_bbio_meta_read() does

/* (3) */ set_extent_buffer_uptodate(eb);

/* (4) */ clear_bit(EXTENT_BUFFER_READING, &eb->bflags);

Normally, this is enough to ensure only one read happens, and all other callers wait for it to finish before returning. Unfortunately, there is a racey interleaving:

Thread A | Thread B | Thread C ---------+----------+--------- (1) | | | (1) | (2) | | (3) | | (4) | | | (2) | | | (1)

When this happens, thread B kicks of an unnecessary read. Worse, thread C will see UPTODATE set and return immediately, while the read from thread B is still in progress. This race could r…

USN-6816-1 — linux, linux-ibm, linux-lowlatency, linux-raspi vulnerabilities

Affected: Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-lowlatency, Ubuntu:24.04:LTS: linux-raspi

Ziming Zhang discovered that the DRM driver for VMware Virtual GPU did not properly handle certain error conditions, leading to a NULL pointer dereference. A local attacker could possibly trigger this vulnerability to cause a denial of service. (CVE-2022-38096)

Zheng Wang discovered that the Broadcom FullMAC WLAN driver in the Linux kernel contained a race condition during device removal, leading to a use- after-free vulnerability. A physically proximate attacker could possibly use this to cause a denial of service (system crash). (CVE-2023-47233)

It was discovered that the ATA over Ethernet (AoE) driver in the Linux kernel contained a race condition, leading to a use-after-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2023-6270)

It was discovered that the Atheros 802.11ac wireless driver did not properly validate certain data structures, leading to a NULL pointer dereference. An attacker could possibly use this to cause a denial of service. (CVE-2023-7042)

It was discovered that the Intel Data Streaming and Intel Analytics Accelerator drivers in the Linux kernel allowed direct access to the devices for unprivileged users and virtual machines. A local attacker could use this to cause a denial of service. (CVE-2024-21823)

Gui-Dong Han discovered that the software RAID driver in the Linux kernel contained a race condition, leading to an integer overflow vulnerability. A privileged attacker could possib…

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CVE-2024-35798 — btrfs: fix race in read_extent_buffer_pages()

USN-6816-1 — linux, linux-ibm, linux-lowlatency, linux-raspi vulnerabilities