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x86_64: Zero extend all registers after ptrace in 32bit entry path.

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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>
This commit is contained in:
Andi Kleen 2007-09-21 16:16:18 +02:00 committed by Linus Torvalds
parent 335fb8fc71
commit 176df2457e
2 changed files with 15 additions and 7 deletions
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18
arch/x86_64/ia32/ia32entry.S
View File

@ -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
@ -152,7 +164,7 @@ 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
@ -255,7 +267,7 @@ 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
@ -334,7 +346,7 @@ 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)

4
arch/x86_64/kernel/ptrace.c
View File

@ -232,10 +232,6 @@ static int putreg(struct task_struct *child,
{
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)