Messages in this thread Patch in this message |  | | | Date | Fri, 06 Nov 2009 14:14:51 -0800 | | From | Greg KH <> | | Subject | [53/99] x86-64: Fix register leak in 32-bit syscall audting |
2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Jan Beulich <JBeulich@novell.com> commit 81766741fe1eee3884219e8daaf03f466f2ed52f upstream.
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> LKML-Reference: <4AE5CC4D020000780001BD13@vpn.id2.novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- arch/x86/ia32/ia32entry.S | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -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:
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