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

While mm->start_stack was protected from cross-uid viewing (commit f83ce3e ("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]>
kyagi · Mar 24, 2011 · 5883f57 · 5883f57
1 parent 312ec7e
commit 5883f57
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/fs/proc/array.c b/fs/proc/array.c
@@ -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,