Linux: Out-of-bounds Write
CVE-2022-48847 is a high-severity out-of-bounds write 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 648895da69ced90ca770fd941c3d9479a9d72c16, 1b09f28f70a5046acd64138075ae3f095238b045, b36588ebbcef74583824c08352e75838d6fb4ff2 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 0.24% 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 648895da69ced90ca770fd941c3d9479a9d72c16 or 1b09f28f70a5046acd64138075ae3f095238b045 or b36588ebbcef74583824c08352e75838d6fb4ff2 or c993ee0f9f81caf5767a50d1faeba39a0dc82af2, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.106 or 5.15.29 or 5.16.15, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c73be61cede5882f9605a852414db559c0ebedfd up to, but not including, 648895da69ced90ca770fd941c3d9479a9d72c16; c73be61cede5882f9605a852414db559c0ebedfd up to, but not including, 1b09f28f70a5046acd64138075ae3f095238b045; c73be61cede5882f9605a852414db559c0ebedfd up to, but not including, b36588ebbcef74583824c08352e75838d6fb4ff2; c73be61cede5882f9605a852414db559c0ebedfd up to, but not including, c993ee0f9f81caf5767a50d1faeba39a0dc82af2; 5.8 | 648895da69ced90ca770fd941c3d9479a9d72c16, 1b09f28f70a5046acd64138075ae3f095238b045, b36588ebbcef74583824c08352e75838d6fb4ff2, c993ee0f9f81caf5767a50d1faeba39a0dc82af2 |
| Linux | Linux Kernel | 5.8 up to, but not including, 5.10.106; 5.11 up to, but not including, 5.15.29; 5.16 up to, but not including, 5.16.15 | 5.10.106, 5.15.29, 5.16.15 |
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: watch_queue: Fix filter limit check In watch_queue_set_filter(), there are a couple of places where we check that the filter type value does not exceed what the type_filter bitmap can hold. One place calculates the number of bits by: if (tf[i].type >= sizeof(wfilter->type_filter) * 8) which is fine, but the second does: if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG) which is not. This can lead to a couple of out-of-bounds writes due to a too-large type: (1) __set_bit() on wfilter->type_filter (2) Writing more elements in wfilter->filters[] than we allocated. Fix this by just using the proper WATCH_TYPE__NR instead, which is the number of types we actually know about. The bug may cause an oops looking something like: BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740 Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611 ... Call Trace: <TASK> dump_stack_lvl+0x45/0x59 print_address_description.constprop.0+0x1f/0x150 ... kasan_report.cold+0x7f/0x11b ... watch_queue_set_filter+0x659/0x740 ... __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Allocated by task 611: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 watch_queue_set_filter+0x23a/0x740 __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88800d2c66a0 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 28 bytes inside of 32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Out-of-bounds Write vulnerabilities
- 8.8 High severity
- 9.1 Critical severity
- 9.6 Critical severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
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