[0/1,SRU,xenial/linux] CVE-2015-1350

[Impact]
The VFS subsystem in the Linux kernel 3.x provides an incomplete set of
requirements for setattr operations that underspecifies removing extended
privilege attributes, which allows local users to cause a denial of service
(capability stripping) via a failed invocation of a system call, as demonstrated
by using chown to remove a capability from the ping or Wireshark dumpcap program.

From the Ubuntu security team:
Ben Harris discovered that the Linux kernel would strip extended privilege
attributes of files when performing a failed unprivileged system call. A
local attacker could use this to cause a denial of service.

The fix commit 030b533c4fd4d2ec3402363323de4bb2983c9cee "fs: Avoid premature
clearing of capabilities" required 3 scaffold patches. I used the stable
updates from linux-4.1.y as a guide.

[Test Plan]
I've run passes with iozone and bonnie++

[Where problems could occur] 
Released in
linux-3.16.y
linux-3.2.y
linux-4.1.y

On 17/03/2021 18:16, Tim Gardner wrote:
> [Impact]
> The VFS subsystem in the Linux kernel 3.x provides an incomplete set of
> requirements for setattr operations that underspecifies removing extended
> privilege attributes, which allows local users to cause a denial of service
> (capability stripping) via a failed invocation of a system call, as demonstrated
> by using chown to remove a capability from the ping or Wireshark dumpcap program.
> 
> From the Ubuntu security team:
> Ben Harris discovered that the Linux kernel would strip extended privilege
> attributes of files when performing a failed unprivileged system call. A
> local attacker could use this to cause a denial of service.
> 
> The fix commit 030b533c4fd4d2ec3402363323de4bb2983c9cee "fs: Avoid premature
> clearing of capabilities" required 3 scaffold patches. I used the stable
> updates from linux-4.1.y as a guide.
> 
> [Test Plan]
> I've run passes with iozone and bonnie++

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>


Best regards,
Krzysztof

On 17.03.21 18:16, Tim Gardner wrote:
> [Impact]
> The VFS subsystem in the Linux kernel 3.x provides an incomplete set of
> requirements for setattr operations that underspecifies removing extended
> privilege attributes, which allows local users to cause a denial of service
> (capability stripping) via a failed invocation of a system call, as demonstrated
> by using chown to remove a capability from the ping or Wireshark dumpcap program.
> 
>  From the Ubuntu security team:
> Ben Harris discovered that the Linux kernel would strip extended privilege
> attributes of files when performing a failed unprivileged system call. A
> local attacker could use this to cause a denial of service.
> 
> The fix commit 030b533c4fd4d2ec3402363323de4bb2983c9cee "fs: Avoid premature
> clearing of capabilities" required 3 scaffold patches. I used the stable
> updates from linux-4.1.y as a guide.
> 
> [Test Plan]
> I've run passes with iozone and bonnie++
> 
> [Where problems could occur]
> Released in
> linux-3.16.y
> linux-3.2.y
> linux-4.1.y
> 
> 
Acked-by: Stefan Bader <stefan.bader@canonical.com>

Applied to xenial/linux-master-next. Thanks.

-rtg

On 3/17/21 11:16 AM, Tim Gardner wrote:
> [Impact]
> The VFS subsystem in the Linux kernel 3.x provides an incomplete set of
> requirements for setattr operations that underspecifies removing extended
> privilege attributes, which allows local users to cause a denial of service
> (capability stripping) via a failed invocation of a system call, as demonstrated
> by using chown to remove a capability from the ping or Wireshark dumpcap program.
> 
>  From the Ubuntu security team:
> Ben Harris discovered that the Linux kernel would strip extended privilege
> attributes of files when performing a failed unprivileged system call. A
> local attacker could use this to cause a denial of service.
> 
> The fix commit 030b533c4fd4d2ec3402363323de4bb2983c9cee "fs: Avoid premature
> clearing of capabilities" required 3 scaffold patches. I used the stable
> updates from linux-4.1.y as a guide.
> 
> [Test Plan]
> I've run passes with iozone and bonnie++
> 
> [Where problems could occur]
> Released in
> linux-3.16.y
> linux-3.2.y
> linux-4.1.y
>