** Description changed:

- Don't allow ptrace to set RIP to a value that couldn't happen by
- ordinary control flow. There are CPU bugs^Wfeatures that can have
- interesting effects if RIP is non-canonical. I didn't make the
- corresponding x86_32 change, since x86_32 has no concept of canonical
- addresses. putreg32 doesn't need this fix: value is only 32 bits, so it
- can't be non-canonical.
+ The Linux kernel before 3.15.4 on Intel processors does not properly
+ restrict use of a non-canonical value for the saved RIP address in the
+ case of a system call that does not use IRET, which allows local users
+ to leverage a race condition and gain privileges, or cause a denial of
+ service (double fault), via a crafted application that makes ptrace and
+ fork system calls.
  
  Break-Fix: 427abfa28afedffadfca9dd8b067eb6d36bac53f
  b9cd18de4db3c9ffa7e17b0dc0ca99ed5aa4d43a

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https://bugs.launchpad.net/bugs/1337339

Title:
  x86_64,ptrace: Enforce RIP <= TASK_SIZE_MAX (CVE-2014-4699)

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