(RHSA-2018:2250) Important: kernel security and bug fix update

ID RHSA-2018:2250
Type redhat
Reporter RedHat
Modified 2018-07-24T22:18:11


The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

  • An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of Load & Store instructions (a commonly used performance optimization). It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory read from address to which a recent memory write has occurred may see an older value and subsequently cause an update into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to read privileged memory by conducting targeted cache side-channel attacks. (CVE-2018-3639, x86 AMD)

Red Hat would like to thank Ken Johnson (Microsoft Security Response Center) and Jann Horn (Google Project Zero) for reporting this issue.

Bug Fix(es):

  • If the cifs_reopen_file() function failed to find a file, the pointer to the cifsFileInfo structure was not reinitialized by being set to "NULL". Subsequently, the find_writable_file() function used an invalid pointer to cifsFileInfo. Consequently, the operating system terminated unexpectedly. With this update, the underlying source code has been fixed to reinitialize the pointer to cifsFileInfo as expected. As a result, the operating system no longer crashes due to this bug. (BZ#1577086)