commit: 5883f57ca0008ffc93e09cbb9847a1928e50c6f3
From: Kees Cook <[email protected]>
Date: Wed, 23 Mar 2011 16:42:53 -0700
Subject: [PATCH] proc: protect mm start_code/end_code in /proc/pid/stat
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 <[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]>
---
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 7c99c1c..5e4f776 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,
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