From: Danny Feng <dfeng@redhat.com>
Date: Tue, 19 Jan 2010 10:30:04 -0500
Subject: [misc] fix kernel info leak with print-fatal-signals=1
Message-id: <20100119103053.19433.12001.sendpatchset@danny>
Patchwork-id: 22647
O-Subject: [PATCH RHEL5.5] CVE-2010-0003 kernel/signal.c: fix kernel information
	leak with print-fatal-signals=1
Bugzilla: 554584
CVE: CVE-2010-0003
RH-Acked-by: Jiri Pirko <jpirko@redhat.com>
RH-Acked-by: Jarod Wilson <jarod@redhat.com>
RH-Acked-by: Dave Anderson <anderson@redhat.com>

Backport upstream commit to fix CVE-2010-0003, which only affects i386 kernel and
with print-fatal-signals=1 (off by default in rhel5)

commit b45c6e76bc2c72f6426c14bed64fdcbc9bf37cb0
Author: Andi Kleen <andi@firstfloor.org>
Date:   Fri Jan 8 14:42:52 2010 -0800

    kernel/signal.c: fix kernel information leak with print-fatal-signals=1

    When print-fatal-signals is enabled it's possible to dump any memory
    reachable by the kernel to the log by simply jumping to that address from
    user space.

    Or crash the system if there's some hardware with read side effects.

    The fatal signals handler will dump 16 bytes at the execution address,
    which is fully controlled by ring 3.

    In addition when something jumps to a unmapped address there will be up to
    16 additional useless page faults, which might be potentially slow (and at
    least is not very efficient)

    Fortunately this option is off by default and only there on i386.

    But fix it by checking for kernel addresses and also stopping when there's
    a page fault.

    Signed-off-by: Andi Kleen <ak@linux.intel.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: <stable@kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Resolves bz554584
Brew build is available at: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=2209396

diff --git a/kernel/signal.c b/kernel/signal.c
index 2b5e7ac..df009a9 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -692,7 +692,8 @@ static void print_fatal_signal(struct pt_regs *regs, int signr)
 		for (i = 0; i < 16; i++) {
 			unsigned char insn;
 
-			__get_user(insn, (unsigned char *)(regs->eip + i));
+			if (get_user(insn, (unsigned char *)(regs->eip + i)))
+				break;
 			printk("%02x ", insn);
 		}
 	}