Уязвимость сервера Network Block Device (NBD) эмулятора аппаратного обеспечения QEMU, позволяющая нарушителю вызвать отказ в обслуживании

Уязвимость ядра операционных систем Linux, Windows, Ubuntu, Debian GNU/Linux, Red Hat Enterprise Linux, macOS, EulerOS, позволяющая нарушителю повысить свои привилегии

A stack-based buffer overflow vulnerability was found in NBD server implementation in qemu before 2.11 allowing a client to request an export name of size up to 4096 bytes, which in fact should be limited to 256 bytes, causing an out-of-bounds stack write in the qemu process. If NBD server requires TLS, the attacker cannot trigger the buffer overflow without first successfully negotiating TLS.

The Network Block Device (NBD) server in Quick Emulator (QEMU) before 2.11 is vulnerable to a denial of service issue. It could occur if a client sent large option requests, making the server waste CPU time on reading up to 4GB per request. A client could use this flaw to keep the NBD server from serving other requests, resulting in DoS.

A statement in the System Programming Guide of the Intel 64 and IA-32 Architectures Software Developer's Manual (SDM) was mishandled in the development of some or all operating-system kernels, resulting in unexpected behavior for #DB exceptions that are deferred by MOV SS or POP SS, as demonstrated by (for example) privilege escalation in Windows, macOS, some Xen configurations, or FreeBSD, or a Linux kernel crash. The MOV to SS and POP SS instructions inhibit interrupts (including NMIs), data breakpoints, and single step trap exceptions until the instruction boundary following the next instruction (SDM Vol. 3A; section 6.8.3). (The inhibited data breakpoints are those on memory accessed by the MOV to SS or POP to SS instruction itself.) Note that debug exceptions are not inhibited by the interrupt enable (EFLAGS.IF) system flag (SDM Vol. 3A; section 2.3). If the instruction following the MOV to SS or POP to SS instruction is an instruction like SYSCALL, SYSENTER, INT 3, etc. that transfers control to the operating system at CPL < 3, the debug exception is delivered after the transfer to CPL < 3 is complete. OS kernels may not expect this order of events and may therefore experience unexpected behavior when it occurs.