Messages in this thread Patch in this message | | | Date | Fri, 28 Jun 2013 09:49:46 -0400 | From | Mathieu Desnoyers <> | Subject | [PATCH 3.10-rc7] Fix: kernel/ptrace.c: ptrace_peek_siginfo() missing __put_user() validation |
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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 <mathieu.desnoyers@efficios.com> CC: Andrey Vagin <avagin@openvz.org> CC: Roland McGrath <roland@redhat.com> CC: Oleg Nesterov <oleg@redhat.com> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: David Howells <dhowells@redhat.com> CC: Dave Jones <davej@redhat.com> CC: Pavel Emelyanov <xemul@parallels.com> CC: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pedro Alves <palves@redhat.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> --- 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
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