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From: Andi Kleen <ak@suse.de>
Date: Fri, 21 Sep 2007 14:16:18 +0000 (+0200)
Subject: x86_64: Zero extend all registers after ptrace in 32bit entry path.
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=176df2457ef6207156ca1a40991c54ca01fef567
x86_64: Zero extend all registers after ptrace in 32bit entry path.
Strictly it's only needed for eax.
It actually does a little more than strictly needed -- the other registers
are already zero extended.
Also remove the now unnecessary and non functional compat task check
in ptrace.
This is CVE-2007-4573
Found by Wojciech Purczynski
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Adjusted to apply to Debian's 2.6.18 by dann frazier <dannf@debian.org>
diff -urpN linux-source-2.6.18.orig/arch/x86_64/ia32/ia32entry.S linux-source-2.6.18/arch/x86_64/ia32/ia32entry.S
--- linux-source-2.6.18.orig/arch/x86_64/ia32/ia32entry.S 2006-09-19 21:42:06.000000000 -0600
+++ linux-source-2.6.18/arch/x86_64/ia32/ia32entry.S 2007-09-25 00:10:16.089100799 -0600
@@ -38,6 +38,18 @@
movq %rax,R8(%rsp)
.endm
+ .macro LOAD_ARGS32 offset
+ movl \offset(%rsp),%r11d
+ movl \offset+8(%rsp),%r10d
+ movl \offset+16(%rsp),%r9d
+ movl \offset+24(%rsp),%r8d
+ movl \offset+40(%rsp),%ecx
+ movl \offset+48(%rsp),%edx
+ movl \offset+56(%rsp),%esi
+ movl \offset+64(%rsp),%edi
+ movl \offset+72(%rsp),%eax
+ .endm
+
.macro CFI_STARTPROC32 simple
CFI_STARTPROC \simple
CFI_UNDEFINED r8
@@ -151,7 +163,7 @@ sysenter_tracesys:
movq $-ENOSYS,RAX(%rsp) /* really needed? */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
- LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */
+ LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
movl %ebp, %ebp
/* no need to do an access_ok check here because rbp has been
@@ -253,7 +265,7 @@ cstar_tracesys:
movq $-ENOSYS,RAX(%rsp) /* really needed? */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
- LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */
+ LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
movl RSP-ARGOFFSET(%rsp), %r8d
/* no need to do an access_ok check here because r8 has been
@@ -330,7 +342,7 @@ ia32_tracesys:
movq $-ENOSYS,RAX(%rsp) /* really needed? */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
- LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */
+ LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
jmp ia32_do_syscall
END(ia32_syscall)
diff -urpN linux-source-2.6.18.orig/arch/x86_64/kernel/ptrace.c linux-source-2.6.18/arch/x86_64/kernel/ptrace.c
--- linux-source-2.6.18.orig/arch/x86_64/kernel/ptrace.c 2006-09-19 21:42:06.000000000 -0600
+++ linux-source-2.6.18/arch/x86_64/kernel/ptrace.c 2007-09-25 00:10:16.089100799 -0600
@@ -223,10 +223,6 @@ static int putreg(struct task_struct *ch
{
unsigned long tmp;
- /* Some code in the 64bit emulation may not be 64bit clean.
- Don't take any chances. */
- if (test_tsk_thread_flag(child, TIF_IA32))
- value &= 0xffffffff;
switch (regno) {
case offsetof(struct user_regs_struct,fs):
if (value && (value & 3) != 3)
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