| From | Paul Gortmaker <> | Subject | [34-longterm 219/247] proc: protect mm start_code/end_code in /proc/pid/stat | Date | Thu, 23 Jun 2011 13:34:47 -0400 |
| |
From: Kees Cook <kees.cook@canonical.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
commit 5883f57ca0008ffc93e09cbb9847a1928e50c6f3 upstream.
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 <kees.cook@canonical.com> 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> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- fs/proc/array.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c index ed2afa6..412e163 100644 --- 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, -- 1.7.4.4
|