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| author | Kees Cook <keescook@chromium.org> | 2012-10-19 13:56:51 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-28 10:02:11 -0700 |
| commit | 58793e9b6ba06d22ce9cf444d190568157c858c9 (patch) | |
| tree | 35f1f0bf217fdc7e9daa1162654a21be0a87c4fd /kernel | |
| parent | 7b48126837ed4804b9f6c1807a21d803cc35172d (diff) | |
| download | lwn-58793e9b6ba06d22ce9cf444d190568157c858c9.tar.gz lwn-58793e9b6ba06d22ce9cf444d190568157c858c9.zip | |
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sys.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index dd29555462c3..46ca435564c4 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1133,15 +1133,16 @@ 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) @@ -1151,8 +1152,9 @@ 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; } |