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

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While mm->start_stack was protected from cross-uid viewing (commit
f83ce3e6b0 ("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>
This commit is contained in:
Kees Cook 2011-03-23 16:42:53 -07:00 committed by Linus Torvalds
parent 312ec7e50c
commit 5883f57ca0
1 changed files with 2 additions and 2 deletions
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4
fs/proc/array.c
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@ -489,8 +489,8 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
vsize, vsize,
mm ? get_mm_rss(mm) : 0, mm ? get_mm_rss(mm) : 0,
rsslim, rsslim,
mm ? mm->start_code : 0, mm ? (permitted ? mm->start_code : 1) : 0,
mm ? mm->end_code : 0, mm ? (permitted ? mm->end_code : 1) : 0,
(permitted && mm) ? mm->start_stack : 0, (permitted && mm) ? mm->start_stack : 0,
esp, esp,
eip, eip,