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CVE-2012-0957: uts: stack memory leak in UNAME26 (rhbz 862877 864824)

This commit is contained in:
Josh Boyer 2012-10-22 09:47:05 -04:00
parent 951aef5850
commit 8431cbd968
2 changed files with 105 additions and 0 deletions
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98
fix-stack-memory-content-leak-via-UNAME26.patch Normal file
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@ -0,0 +1,98 @@
From 2702b1526c7278c4d65d78de209a465d4de2885e Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Fri, 19 Oct 2012 13:56:51 -0700
Subject: [PATCH 1/2] kernel/sys.c: fix stack memory content leak via UNAME26
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>
Cc: <stable@vger.kernel.org>
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;
}
--
1.7.12.1
From 31fd84b95eb211d5db460a1dda85e004800a7b52 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Fri, 19 Oct 2012 18:45:53 -0700
Subject: [PATCH 2/2] use clamp_t in UNAME26 fix
The min/max call needed to have explicit types on some architectures
(e.g. mn10300). Use clamp_t instead to avoid the warning:
kernel/sys.c: In function 'override_release':
kernel/sys.c:1287:10: warning: comparison of distinct pointer types lacks a cast [enabled by default]
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/sys.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index 01865c6..e6e0ece 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1284,7 +1284,7 @@ static int override_release(char __user *release, size_t len)
rest++;
}
v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
- copy = min(sizeof(buf), max_t(size_t, 1, len));
+ copy = clamp_t(size_t, len, 1, sizeof(buf));
copy = scnprintf(buf, copy, "2.6.%u%s", v, rest);
ret = copy_to_user(release, buf, copy + 1);
}
--
1.7.12.1

7
kernel.spec
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@ -756,6 +756,9 @@ Patch22074: mac80211-connect-with-HT20-if-HT40-is-not-permitted.patch
#rhbz 856863
Patch22075: rt2x00-usb-fix-reset-resume.patch
#rhbz 862877 864824 CVE-2012-0957
Patch22076: fix-stack-memory-content-leak-via-UNAME26.patch
Patch22072: linux-3.6-arm-build-fixup.patch
# END OF PATCH DEFINITIONS
@ -1465,6 +1468,9 @@ ApplyPatch mac80211-connect-with-HT20-if-HT40-is-not-permitted.patch
#rhbz 856863
ApplyPatch rt2x00-usb-fix-reset-resume.patch
#rhbz 862877 864824 CVE-2012-0957
ApplyPatch fix-stack-memory-content-leak-via-UNAME26.patch
# END OF PATCH APPLICATIONS
%endif
@ -2329,6 +2335,7 @@ fi
# '-'
%changelog
* Mon Oct 22 2012 Josh Boyer <jwboyer@redhat.com>
- CVE-2012-0957: uts: stack memory leak in UNAME26 (rhbz 862877 864824)
- Fix rt2x00 usb reset resume (rhbz 856863)
- Linux v3.6.3