| 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-2024-49870: cachefiles: fix dentry leak in cachefiles_open_file() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| cachefiles: fix dentry leak in cachefiles_open_file() |
| |
| A dentry leak may be caused when a lookup cookie and a cull are concurrent: |
| |
| P1 | P2 |
| ----------------------------------------------------------- |
| cachefiles_lookup_cookie |
| cachefiles_look_up_object |
| lookup_one_positive_unlocked |
| // get dentry |
| cachefiles_cull |
| inode->i_flags |= S_KERNEL_FILE; |
| cachefiles_open_file |
| cachefiles_mark_inode_in_use |
| __cachefiles_mark_inode_in_use |
| can_use = false |
| if (!(inode->i_flags & S_KERNEL_FILE)) |
| can_use = true |
| return false |
| return false |
| // Returns an error but doesn't put dentry |
| |
| After that the following WARNING will be triggered when the backend folder |
| is umounted: |
| |
| ================================================================== |
| BUG: Dentry 000000008ad87947{i=7a,n=Dx_1_1.img} still in use (1) [unmount of ext4 sda] |
| WARNING: CPU: 4 PID: 359261 at fs/dcache.c:1767 umount_check+0x5d/0x70 |
| CPU: 4 PID: 359261 Comm: umount Not tainted 6.6.0-dirty #25 |
| RIP: 0010:umount_check+0x5d/0x70 |
| Call Trace: |
| <TASK> |
| d_walk+0xda/0x2b0 |
| do_one_tree+0x20/0x40 |
| shrink_dcache_for_umount+0x2c/0x90 |
| generic_shutdown_super+0x20/0x160 |
| kill_block_super+0x1a/0x40 |
| ext4_kill_sb+0x22/0x40 |
| deactivate_locked_super+0x35/0x80 |
| cleanup_mnt+0x104/0x160 |
| ================================================================== |
| |
| Whether cachefiles_open_file() returns true or false, the reference count |
| obtained by lookup_positive_unlocked() in cachefiles_look_up_object() |
| should be released. |
| |
| Therefore release that reference count in cachefiles_look_up_object() to |
| fix the above issue and simplify the code. |
| |
| The Linux kernel CVE team has assigned CVE-2024-49870 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit 1f08c925e7a38002bde509e66f6f891468848511 and fixed in 6.1.113 with commit d32ff64c872d7e08e893c32ba6a2374583444410 |
| Issue introduced in 5.17 with commit 1f08c925e7a38002bde509e66f6f891468848511 and fixed in 6.6.55 with commit c7d10fa7d7691558ff967668494672415f5fa151 |
| Issue introduced in 5.17 with commit 1f08c925e7a38002bde509e66f6f891468848511 and fixed in 6.10.14 with commit e4a28489b310339b2b8187bec0a437709be551c1 |
| Issue introduced in 5.17 with commit 1f08c925e7a38002bde509e66f6f891468848511 and fixed in 6.11.3 with commit 7fa2382f97421978514a419c93054eca69f5247b |
| Issue introduced in 5.17 with commit 1f08c925e7a38002bde509e66f6f891468848511 and fixed in 6.12 with commit da6ef2dffe6056aad3435e6cf7c6471c2a62187c |
| |
| 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-2024-49870 |
| 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/cachefiles/namei.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/d32ff64c872d7e08e893c32ba6a2374583444410 |
| https://git.kernel.org/stable/c/c7d10fa7d7691558ff967668494672415f5fa151 |
| https://git.kernel.org/stable/c/e4a28489b310339b2b8187bec0a437709be551c1 |
| https://git.kernel.org/stable/c/7fa2382f97421978514a419c93054eca69f5247b |
| https://git.kernel.org/stable/c/da6ef2dffe6056aad3435e6cf7c6471c2a62187c |
