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.desnoy...@efficios.com>
CC: Andrey Vagin <ava...@openvz.org>
CC: Roland McGrath <rol...@redhat.com>
CC: Oleg Nesterov <o...@redhat.com>
CC: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
CC: David Howells <dhowe...@redhat.com>
CC: Dave Jones <da...@redhat.com>
CC: Pavel Emelyanov <xe...@parallels.com>
CC: Linus Torvalds <torva...@linux-foundation.org>
Cc: Pedro Alves <pal...@redhat.com>
CC: Andrew Morton <a...@linux-foundation.org>
CC: Linus Torvalds <torva...@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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