61 lines
2.0 KiB
Diff
61 lines
2.0 KiB
Diff
From: Kees Cook <keescook@chromium.org>
|
|
Date: Fri, 19 Oct 2012 13:56:51 -0700
|
|
Subject: [1/2] kernel/sys.c: fix stack memory content leak via UNAME26
|
|
|
|
commit 2702b1526c7278c4d65d78de209a465d4de2885e upstream.
|
|
|
|
Calling uname() with the UNAME26 personality set allows a leak of kernel
|
|
stack contents. This fixes it by defensively calculating the length of
|
|
copy_to_user() call, making the len argument unsigned, and initializing
|
|
the stack buffer to zero (now technically unneeded, but hey, overkill).
|
|
|
|
CVE-2012-0957
|
|
|
|
Reported-by: PaX Team <pageexec@freemail.hu>
|
|
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Cc: Andi Kleen <ak@linux.intel.com>
|
|
Cc: PaX Team <pageexec@freemail.hu>
|
|
Cc: Brad Spengler <spender@grsecurity.net>
|
|
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
---
|
|
kernel/sys.c | 12 +++++++-----
|
|
1 file changed, 7 insertions(+), 5 deletions(-)
|
|
|
|
diff --git a/kernel/sys.c b/kernel/sys.c
|
|
index c5cb5b9..01865c6 100644
|
|
--- a/kernel/sys.c
|
|
+++ b/kernel/sys.c
|
|
@@ -1265,15 +1265,16 @@ DECLARE_RWSEM(uts_sem);
|
|
* Work around broken programs that cannot handle "Linux 3.0".
|
|
* Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
|
|
*/
|
|
-static int override_release(char __user *release, int len)
|
|
+static int override_release(char __user *release, size_t len)
|
|
{
|
|
int ret = 0;
|
|
- char buf[65];
|
|
|
|
if (current->personality & UNAME26) {
|
|
- char *rest = UTS_RELEASE;
|
|
+ const char *rest = UTS_RELEASE;
|
|
+ char buf[65] = { 0 };
|
|
int ndots = 0;
|
|
unsigned v;
|
|
+ size_t copy;
|
|
|
|
while (*rest) {
|
|
if (*rest == '.' && ++ndots >= 3)
|
|
@@ -1283,8 +1284,9 @@ static int override_release(char __user *release, int len)
|
|
rest++;
|
|
}
|
|
v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
|
|
- snprintf(buf, len, "2.6.%u%s", v, rest);
|
|
- ret = copy_to_user(release, buf, len);
|
|
+ copy = min(sizeof(buf), max_t(size_t, 1, len));
|
|
+ copy = scnprintf(buf, copy, "2.6.%u%s", v, rest);
|
|
+ ret = copy_to_user(release, buf, copy + 1);
|
|
}
|
|
return ret;
|
|
}
|