Linux: Use After Free
CVE-2022-50507 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions de5e0955248ff90a2ae91e7f5c108392b52152d0, e0455361d3068066a91fe18282b751925d7b5ee7, 9173b89c16a603d73c434b695fe2a7a13491300f as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.16% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to de5e0955248ff90a2ae91e7f5c108392b52152d0 or e0455361d3068066a91fe18282b751925d7b5ee7 or 9173b89c16a603d73c434b695fe2a7a13491300f or 6db620863f8528ed9a9aa5ad323b26554a17881d, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.87 or 6.0.17 or 6.1.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 82cae269cfa953032fbb8980a7d554d60fb00b17 up to, but not including, de5e0955248ff90a2ae91e7f5c108392b52152d0; 82cae269cfa953032fbb8980a7d554d60fb00b17 up to, but not including, e0455361d3068066a91fe18282b751925d7b5ee7; 82cae269cfa953032fbb8980a7d554d60fb00b17 up to, but not including, 9173b89c16a603d73c434b695fe2a7a13491300f; 82cae269cfa953032fbb8980a7d554d60fb00b17 up to, but not including, 6db620863f8528ed9a9aa5ad323b26554a17881d; 5.15 | de5e0955248ff90a2ae91e7f5c108392b52152d0, e0455361d3068066a91fe18282b751925d7b5ee7, 9173b89c16a603d73c434b695fe2a7a13491300f, 6db620863f8528ed9a9aa5ad323b26554a17881d |
| Linux | Linux Kernel | 5.15 up to, but not including, 5.15.87; 5.16 up to, but not including, 6.0.17; 6.1 up to, but not including, 6.1.3 | 5.15.87, 6.0.17, 6.1.3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Validate data run offset This adds sanity checks for data run offset. We should make sure data run offset is legit before trying to unpack them, otherwise we may encounter use-after-free or some unexpected memory access behaviors. [ 82.940342] BUG: KASAN: use-after-free in run_unpack+0x2e3/0x570 [ 82.941180] Read of size 1 at addr ffff888008a8487f by task mount/240 [ 82.941670] [ 82.942069] CPU: 0 PID: 240 Comm: mount Not tainted 5.19.0+ #15 [ 82.942482] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 82.943720] Call Trace: [ 82.944204] <TASK> [ 82.944471] dump_stack_lvl+0x49/0x63 [ 82.944908] print_report.cold+0xf5/0x67b [ 82.945141] ? __wait_on_bit+0x106/0x120 [ 82.945750] ? run_unpack+0x2e3/0x570 [ 82.946626] kasan_report+0xa7/0x120 [ 82.947046] ? run_unpack+0x2e3/0x570 [ 82.947280] __asan_load1+0x51/0x60 [ 82.947483] run_unpack+0x2e3/0x570 [ 82.947709] ? memcpy+0x4e/0x70 [ 82.947927] ? run_pack+0x7a0/0x7a0 [ 82.948158] run_unpack_ex+0xad/0x3f0 [ 82.948399] ? mi_enum_attr+0x14a/0x200 [ 82.948717] ? run_unpack+0x570/0x570 [ 82.949072] ? ni_enum_attr_ex+0x1b2/0x1c0 [ 82.949332] ? ni_fname_type.part.0+0xd0/0xd0 [ 82.949611] ? mi_read+0x262/0x2c0 [ 82.949970] ? ntfs_cmp_names_cpu+0x125/0x180 [ 82.950249] ntfs_iget5+0x632/0x1870 [ 82.950621] ? ntfs_get_block_bmap+0x70/0x70 [ 82.951192] ? evict+0x223/0x280 [ 82.951525] ? iput.part.0+0x286/0x320 [ 82.951969] ntfs_fill_super+0x1321/0x1e20 [ 82.952436] ? put_ntfs+0x1d0/0x1d0 [ 82.952822] ? vsprintf+0x20/0x20 [ 82.953188] ? mutex_unlock+0x81/0xd0 [ 82.953379] ? set_blocksize+0x95/0x150 [ 82.954001] get_tree_bdev+0x232/0x370 [ 82.954438] ? put_ntfs+0x1d0/0x1d0 [ 82.954700] ntfs_fs_get_tree+0x15/0x20 [ 82.955049] vfs_get_tree+0x4c/0x130 [ 82.955292] path_mount+0x645/0xfd0 [ 82.955615] ? putname+0x80/0xa0 [ 82.955955] ? finish_automount+0x2e0/0x2e0 [ 82.956310] ? kmem_cache_free+0x110/0x390 [ 82.956723] ? putname+0x80/0xa0 [ 82.957023] do_mount+0xd6/0xf0 [ 82.957411] ? path_mount+0xfd0/0xfd0 [ 82.957638] ? __kasan_check_write+0x14/0x20 [ 82.957948] __x64_sys_mount+0xca/0x110 [ 82.958310] do_syscall_64+0x3b/0x90 [ 82.958719] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 82.959341] RIP: 0033:0x7fd0d1ce948a [ 82.960193] Code: 48 8b 0d 11 fa 2a 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 008 [ 82.961532] RSP: 002b:00007ffe59ff69a8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5 [ 82.962527] RAX: ffffffffffffffda RBX: 0000564dcc107060 RCX: 00007fd0d1ce948a [ 82.963266] RDX: 0000564dcc107260 RSI: 0000564dcc1072e0 RDI: 0000564dcc10fce0 [ 82.963686] RBP: 0000000000000000 R08: 0000564dcc107280 R09: 0000000000000020 [ 82.964272] R10: 00000000c0ed0000 R11: 0000000000000202 R12: 0000564dcc10fce0 [ 82.964785] R13: 0000564dcc107260 R14: 0000000000000000 R15: 00000000ffffffff
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
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