Commit 5883f57c authored Mar 23, 2011 by Kees Cook Committed by Linus Torvalds Mar 23, 2011

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



While mm->start_stack was protected from cross-uid viewing (commit
f83ce3e6 ("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 <kees.cook@canonical.com>
Cc: <stable@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Eugene Teo <eugeneteo@kernel.sg>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 312ec7e5

fs/proc/array.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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,

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