CVE: integer overflow in the Linux kernel when handling TCP Selective Acknowledgments (SACKs)

[zhao.shuai]

Brief Description
-----------------
Security Vulnerability(es):

An integer overflow flaw was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented. Each fragment is about TCP maximum segment size (MSS) bytes. To efficiently process SACK blocks, the Linux kernel merges multiple fragmented SKBs into one, potentially overflowing the variable holding the number of segments. A remote attacker could use this flaw to crash the Linux kernel by sending a crafted sequence of SACK segments on a TCP connection with small value of TCP MSS, resulting in a denial of service (DoS). (CVE-2019-11477)
Kernel: tcp: excessive resource consumption while processing SACK blocks allows remote denial of service (CVE-2019-11478)
Kernel: tcp: excessive resource consumption for TCP connections with low MSS allows remote denial of service (CVE-2019-11479)

Redhat Description：
https://access.redhat.com/errata/RHSA-2019:1481
https://access.redhat.com/errata/RHSA-2019:1486

kernel:
http://vault.centos.org/7.6.1810/updates/Source/SPackages/kernel-3.10.0-957.21.3.el7.src.rpm

kernel-rt:
http://linuxsoft.cern.ch/cern/centos/7.6/rt/Source/SPackages/kernel-rt-3.10.0-957.21.3.rt56.935.el7.src.rpm

[zhao.shuai (zhao.shuai)]

Regarding kernel minor version upgrade which we discussed in the meeting,
we've reached consensus with Ken Young and other security team members:
For the below two options we had:
     Option#1: upgrade the kernel 21.3 in the master only;
     Option#2: only cherry pick the security patch to address CVE-11477.

Conclusion is that we will stick with Option#1: put the kernel upgrade
into master after RC1 branched out; then we continue to do testing on master;
if everything goes well, we can cherry pick the patches to release branch.
continue the upgrade in master with Workflow -1 for now till RC1.

Option#1 Patches:
https://review.opendev.org/#/c/670856/
https://review.opendev.org/#/c/670870/
https://review.opendev.org/#/c/670869/

Option#2 Patches:
https://review.opendev.org/#/c/670711/

[Ghada Khalil (gkhalil)]

As discussed with Cindy, Ken & Brent, after sufficient testing, the kernel upgrade should be backported to the stx.2.0 release branch.

[zhao.shuai (zhao.shuai.neusoft)]

The current stx.2.0 version branch has been switched, and this security vulnerability issue is expected to be incorporated into our master branch.

We conducted manual testing and Sanity testing. The test results of AIO are all passed. Duplex test results are consistent with official ISO test results.

So now workflow-1 is removed.I hope the experts can give the review again. Thank you！

[Ghada Khalil (gkhalil)]

The following patches were merged in stx master on 2019-08-19 to address this vulnerability:
https://review.opendev.org/#/c/670856/
https://review.opendev.org/#/c/670870/
https://review.opendev.org/#/c/670869/

The next step is to cherrypick the changes to the r/stx.2.0 branch

[zhao.shuai (zhao.shuai.neusoft)]

At present, the cherry-pick work has just finished
the merge in the local code repository and compile.

but we hope to submit the patch package after a basic test.
The Cherry-pick is expected to be submitted to Gerrit within the next Monday.

[Ghada Khalil (gkhalil)]

Changes are merged in r/stx.2.0:
https://review.opendev.org/#/c/682204/
https://review.opendev.org/#/c/682197/
https://review.opendev.org/#/c/682194/