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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: Jan Beulich <jbeulich@novell.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: <stable@kernel.org>
LKML-Reference: <4AE5CC4D020000780001BD13@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jan Beulich 2009-10-26 15:20:29 +00:00 committed by Ingo Molnar
parent 72ed7de74e
commit 81766741fe
1 changed files with 2 additions and 3 deletions
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5
arch/x86/ia32/ia32entry.S
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@ -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: