CVE-2022-49859

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

net: lapbether: fix issue of invalid opcode in lapbeth_open()

If lapb_register() failed when lapb device goes to up for the first time, the NAPI is not disabled. As a result, the invalid opcode issue is reported when the lapb device goes to up for the second time.

The stack info is as follows: [ 1958.311422][T11356] kernel BUG at net/core/dev.c:6442! [ 1958.312206][T11356] invalid opcode: 0000 [#1] PREEMPT SMP KASAN [ 1958.315979][T11356] RIP: 0010:napi_enable+0x16a/0x1f0 [ 1958.332310][T11356] Call Trace: [ 1958.332817][T11356] [ 1958.336135][T11356] lapbeth_open+0x18/0x90 [ 1958.337446][T11356] __dev_open+0x258/0x490 [ 1958.341672][T11356] __dev_change_flags+0x4d4/0x6a0 [ 1958.345325][T11356] dev_change_flags+0x93/0x160 [ 1958.346027][T11356] devinet_ioctl+0x1276/0x1bf0 [ 1958.346738][T11356] inet_ioctl+0x1c8/0x2d0 [ 1958.349638][T11356] sock_ioctl+0x5d1/0x750 [ 1958.356059][T11356] __x64_sys_ioctl+0x3ec/0x1790 [ 1958.365594][T11356] do_syscall_64+0x35/0x80 [ 1958.366239][T11356] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 1958.377381][T11356]

Weakness

The product writes data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• 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 [REF-57], and the Strsafe.h library from Microsoft [REF-56]. 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 [REF-1334] discusses canary-based detection in detail.

• Consider adhering to the following rules when allocating and managing an application’s memory:

• Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

• Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

• For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

• Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

• For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

References

• https://git.kernel.org/stable/c/3faf7e14ec0c3462c2d747fa6793b8645d1391df
• https://git.kernel.org/stable/c/4689bd3a1b23a1bd917899e63b81bca2ccdfab45
• https://git.kernel.org/stable/c/ed4940050a7ce7fc2ccd51db580ef1ade64290b1