proc: protect mm start_code/end_code in /proc/pid/stat

While mm->start_stack was protected from cross-uid viewing (commit
f83ce3e6b02d5 ("proc: avoid information leaks to non-privileged
processes")), the start_code and end_code values were not.  This would
allow the text location of a PIE binary to leak, defeating ASLR.

Note that the value "1" is used instead of "0" for a protected value since
"ps", "killall", and likely other readers of /proc/pid/stat, take
start_code of "0" to mean a kernel thread and will misbehave.  Thanks to
Brad Spengler for pointing this out.

Addresses CVE-2011-0726

Signed-off-by: Kees Cook <[email protected]>
Cc: <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: David Howells <[email protected]>
Cc: Eugene Teo <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Brad Spengler <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions