Messages in this thread Patch in this message | | | Date | Fri, 25 Mar 2011 17:03:52 -0700 | From | Greg KH <> | Subject | [20/35] proc: protect mm start_code/end_code in /proc/pid/stat |
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2.6.33-longterm review patch. If anyone has any objections, please let us know.
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From: Kees Cook <kees.cook@canonical.com>
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: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/proc/array.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -488,8 +488,8 @@ static int do_task_stat(struct seq_file 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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