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Commit 81766741 authored by Jan Beulich's avatar Jan Beulich Committed by Ingo Molnar
Browse files

x86-64: Fix register leak in 32-bit syscall audting 



Restoring %ebp after the call to audit_syscall_exit() is not
only unnecessary (because the register didn't get clobbered),
but in the sysenter case wasn't even doing the right thing: It
loaded %ebp from a location below the top of stack (RBP <
ARGOFFSET), i.e. arbitrary kernel data got passed back to user
mode in the register.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Cc: <stable@kernel.org>
LKML-Reference: <4AE5CC4D020000780001BD13@vpn.id2.novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 72ed7de7

arch/x86/ia32/ia32entry.S

+2 −3
Original line number Diff line number Diff line
@@ -204,7 +204,7 @@ sysexit_from_sys_call: 
	movl RDI-ARGOFFSET(%rsp),%r8d	/* reload 5th syscall arg */

	.endm



	.macro auditsys_exit exit,ebpsave=RBP

	.macro auditsys_exit exit

	testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)

	jnz ia32_ret_from_sys_call

	TRACE_IRQS_ON
@@ -217,7 +217,6 @@ sysexit_from_sys_call: 
	call audit_syscall_exit

	GET_THREAD_INFO(%r10)

	movl RAX-ARGOFFSET(%rsp),%eax	/* reload syscall return value */

	movl \ebpsave-ARGOFFSET(%rsp),%ebp /* reload user register value */

	movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi

	cli

	TRACE_IRQS_OFF
@@ -351,7 +350,7 @@ cstar_auditsys: 
	jmp cstar_dispatch



sysretl_audit:

	auditsys_exit sysretl_from_sys_call, RCX /* user %ebp in RCX slot */

	auditsys_exit sysretl_from_sys_call

#endif



cstar_tracesys: