proc: protect mm start_code/end_code in /proc/pid/stat
PATCH 1/1 proc: protect mm start_code/end_code in /proc/pid/stat
While mm->start_stack was protected from cross-uid viewing (commit f83ce3e6b02d5e48b3a43b001390e2b58820389d), 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.
CVE-2011-0726
Signed-off-by Kees Cook <[email protected]>
--- fs/proc/array.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
fs/proc/array.c +2 -2
@@ -489,8 +489,8 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, vsize, mm ?get_mm_rss (mm) :0 , rsslim, - mm ? mm->start_code :0 , - mm ? mm->end_code :0 , + mm ? (permitted ? mm->start_code :1 ) :0 , + mm ? (permitted ? mm->end_code :1 ) :0 , (permitted && mm) ? mm->start_stack :0 , esp, eip,
Signature · 5 lines
1.7.4.1 -- Kees Cook Ubuntu Security Team