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authorKees Cook <keescook@chromium.org>2012-10-19 13:56:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-19 14:07:47 -0700
commit2702b1526c7278c4d65d78de209a465d4de2885e (patch)
treea41af3d56a6e37af19bc7ed392f2580750ba86cb /kernel/sys.c
parent1d46e232f8637f31f8df2e50b27fd20d8135bd93 (diff)
downloadlinux-linaro-stable-2702b1526c7278c4d65d78de209a465d4de2885e.tar.gz
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>
Diffstat (limited to 'kernel/sys.c')
-rw-r--r--kernel/sys.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index c5cb5b99cb81..01865c6fb6a0 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;
}