| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-56755: netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING |
| |
| In fscache_create_volume(), there is a missing memory barrier between the |
| bit-clearing operation and the wake-up operation. This may cause a |
| situation where, after a wake-up, the bit-clearing operation hasn't been |
| detected yet, leading to an indefinite wait. The triggering process is as |
| follows: |
| |
| [cookie1] [cookie2] [volume_work] |
| fscache_perform_lookup |
| fscache_create_volume |
| fscache_perform_lookup |
| fscache_create_volume |
| fscache_create_volume_work |
| cachefiles_acquire_volume |
| clear_and_wake_up_bit |
| test_and_set_bit |
| test_and_set_bit |
| goto maybe_wait |
| goto no_wait |
| |
| In the above process, cookie1 and cookie2 has the same volume. When cookie1 |
| enters the -no_wait- process, it will clear the bit and wake up the waiting |
| process. If a barrier is missing, it may cause cookie2 to remain in the |
| -wait- process indefinitely. |
| |
| In commit 3288666c7256 ("fscache: Use clear_and_wake_up_bit() in |
| fscache_create_volume_work()"), barriers were added to similar operations |
| in fscache_create_volume_work(), but fscache_create_volume() was missed. |
| |
| By combining the clear and wake operations into clear_and_wake_up_bit() to |
| fix this issue. |
| |
| The Linux kernel CVE team has assigned CVE-2024-56755 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit bfa22da3ed652aa15acd4246fa13a0de6dbe4a59 and fixed in 6.1.120 with commit ddab02607eed9e415dc62fde421d4329e5345315 |
| Issue introduced in 5.17 with commit bfa22da3ed652aa15acd4246fa13a0de6dbe4a59 and fixed in 6.6.64 with commit 539fabba965e119b98066fc6ba5257b5eaf4eda2 |
| Issue introduced in 5.17 with commit bfa22da3ed652aa15acd4246fa13a0de6dbe4a59 and fixed in 6.11.11 with commit 8beb682cc9a0798a280bbb95e3e41617237090b2 |
| Issue introduced in 5.17 with commit bfa22da3ed652aa15acd4246fa13a0de6dbe4a59 and fixed in 6.12.2 with commit 8cc1df3113cb71a0df2c46dd5b102c9e11c8a8c6 |
| Issue introduced in 5.17 with commit bfa22da3ed652aa15acd4246fa13a0de6dbe4a59 and fixed in 6.13 with commit 22f9400a6f3560629478e0a64247b8fcc811a24d |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-56755 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/netfs/fscache_volume.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/ddab02607eed9e415dc62fde421d4329e5345315 |
| https://git.kernel.org/stable/c/539fabba965e119b98066fc6ba5257b5eaf4eda2 |
| https://git.kernel.org/stable/c/8beb682cc9a0798a280bbb95e3e41617237090b2 |
| https://git.kernel.org/stable/c/8cc1df3113cb71a0df2c46dd5b102c9e11c8a8c6 |
| https://git.kernel.org/stable/c/22f9400a6f3560629478e0a64247b8fcc811a24d |
