This __put_user() could be used by unprivileged processes to write into kernel memory. The issue here is that even if copy_siginfo_to_user() fails, the error code is not checked before __put_user() is executed. Luckily, ptrace_peek_siginfo() has been added within the 3.10-rc cycle, so it has not hit a stable release yet.
Signed-off-by: Mathieu Desnoyers <[email protected]> CC: Andrey Vagin <[email protected]> CC: Roland McGrath <[email protected]> CC: Oleg Nesterov <[email protected]> CC: "Paul E. McKenney" <[email protected]> CC: David Howells <[email protected]> CC: Dave Jones <[email protected]> CC: Pavel Emelyanov <[email protected]> CC: Linus Torvalds <[email protected]> Cc: Pedro Alves <[email protected]> CC: Andrew Morton <[email protected]> CC: Linus Torvalds <[email protected]> --- kernel/ptrace.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) Index: linux/kernel/ptrace.c =================================================================== --- linux.orig/kernel/ptrace.c +++ linux/kernel/ptrace.c @@ -665,20 +665,22 @@ static int ptrace_peek_siginfo(struct ta if (unlikely(is_compat_task())) { compat_siginfo_t __user *uinfo = compat_ptr(data); - ret = copy_siginfo_to_user32(uinfo, &info); - ret |= __put_user(info.si_code, &uinfo->si_code); + if (copy_siginfo_to_user32(uinfo, &info) || + __put_user(info.si_code, &uinfo->si_code)) { + ret = -EFAULT; + break; + } + } else #endif { siginfo_t __user *uinfo = (siginfo_t __user *) data; - ret = copy_siginfo_to_user(uinfo, &info); - ret |= __put_user(info.si_code, &uinfo->si_code); - } - - if (ret) { - ret = -EFAULT; - break; + if (copy_siginfo_to_user(uinfo, &info) || + __put_user(info.si_code, &uinfo->si_code)) { + ret = -EFAULT; + break; + } } data += sizeof(siginfo_t); -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
