[patch 09/23] i386: fixup TRACE_IRQ breakage (CVE-2007-3731)

[Greg KH]

2.6.22-stable review patch.  If anyone has any objections, please let us
know.

------------------

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

mainline: a10d9a71bafd3a283da240d2868e71346d2aef6f

The TRACE_IRQS_ON function in iret_exc: calls a C function without
ensuring that the segments are set properly. Move the trace function and
the enabling of interrupt into the C stub.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Jeff Mahoney <jeffm@xxxxxxxx>
CC: Oliver Pinter <oliver.pntr@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/i386/kernel/entry.S |    2 --
 arch/i386/kernel/traps.c |   10 ++++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -409,8 +409,6 @@ restore_nocheck_notrace:
 1:	INTERRUPT_RETURN
 .section .fixup,"ax"
 iret_exc:
-	TRACE_IRQS_ON
-	ENABLE_INTERRUPTS(CLBR_NONE)
 	pushl $0			# no error code
 	pushl $do_iret_error
 	jmp error_code
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -517,10 +517,12 @@ fastcall void do_##name(struct pt_regs *
 	do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
 }
 
-#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
+#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr, irq) \
 fastcall void do_##name(struct pt_regs * regs, long error_code) \
 { \
 	siginfo_t info; \
+	if (irq) \
+		local_irq_enable(); \
 	info.si_signo = signr; \
 	info.si_errno = 0; \
 	info.si_code = sicode; \
@@ -560,13 +562,13 @@ DO_VM86_ERROR( 3, SIGTRAP, "int3", int3)
 #endif
 DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow)
 DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds)
-DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip)
+DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip, 0)
 DO_ERROR( 9, SIGFPE,  "coprocessor segment overrun", coprocessor_segment_overrun)
 DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)
 DO_ERROR(12, SIGBUS,  "stack segment", stack_segment)
-DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
-DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0)
+DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0, 0)
+DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0, 1)
 
 fastcall void __kprobes do_general_protection(struct pt_regs * regs,
 					      long error_code)

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