ACK: [PATCH 0/1] [SRU] [focal/linux-oem-5.6] CVE-2020-10781: zram oom

[Stefan Bader]

On 12.03.21 18:32, Tim Gardner wrote:
> [Impact]
> A flaw was found in the Linux Kernel before 5.8-rc6 in the ZRAM kernel module,
> where a user with a local account and the ability to read the
> /sys/class/zram-control/hot_add file can create ZRAM device nodes in the /dev/
> directory. This read allocates kernel memory and is not accounted for a user
> that triggers the creation of that ZRAM device. With this vulnerability,
> continually reading the device may consume a large amount of system memory
> and cause the Out-of-Memory (OOM) killer to activate and terminate random
> userspace processes, possibly making the system inoperable.
> 
>  From the Ubuntu security team:
> Luca Bruno discovered that the zram module in the Linux kernel did not properly
> restrict unprivileged users from accessing the hot_add sysfs file. A local
> attacker could use this to cause a denial of service (memory exhaustion).
> 
> [Test Case]
> none
> 
> [Potential regression]
> Released in
> linux-4.14.y
> linux-4.19.y
> linux-5.4.y
> linux-5.7.y
> 
> 
> 
Acked-by: Stefan Bader <stefan.bader at canonical.com>

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