[email protected] wrote:
The patch titled
i386: fix get_segment_eip() with vm86 segments
has been added to the -mm tree. Its filename is
i386-fix-get_segment_eip-with-vm86.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: i386: fix get_segment_eip() with vm86 segments
From: Chuck Ebbert <[email protected]>
We need to check for vm86 mode first before looking at selector privilege
bits.
Segment limit is always base + 64k and only the low 16 bits of EIP are
significant in vm86 mode.
Signed-off-by: Chuck Ebbert <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Zachary Amsden <[email protected]>
Cc: Rohit Seth <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
arch/i386/mm/fault.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff -puN arch/i386/mm/fault.c~i386-fix-get_segment_eip-with-vm86 arch/i386/mm/fault.c
--- devel/arch/i386/mm/fault.c~i386-fix-get_segment_eip-with-vm86 2006-05-29 20:06:19.000000000 -0700
+++ devel-akpm/arch/i386/mm/fault.c 2006-05-29 20:06:19.000000000 -0700
@@ -77,12 +77,15 @@ static inline unsigned long get_segment_
unsigned seg = regs->xcs & 0xffff;
u32 seg_ar, seg_limit, base, *desc;
+ /* Unlikely, but must come before segment checks. */
+ if (unlikely(regs->eflags & VM_MASK)) {
+ base = seg << 4;
+ *eip_limit = base + 0xffff;
+ return base + (eip & 0xffff);
+ }
+
/* The standard kernel/user address space limit. */
*eip_limit = (seg & 3) ? USER_DS.seg : KERNEL_DS.seg;
-
- /* Unlikely, but must come before segment checks. */
- if (unlikely((regs->eflags & VM_MASK) != 0))
- return eip + (seg << 4);
/* By far the most common cases. */
if (likely(seg == __USER_CS || seg == __KERNEL_CS))
_
Patches currently in -mm which might be from [email protected] are
i386-let-usermode-execute-the-enter.patch
i386-fix-get_segment_eip-with-vm86.patch
This looks great. While we're in the spirit let's fix kprobes v8086
handling as well by filtering out int3s from v8086 mode.
Never allow int3 traps from V8086 mode to enter the kprobes handler.
Signed-off-by: Zachary Amsden <[email protected]>
Index: linux-2.6.17-rc/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6.17-rc.orig/arch/i386/kernel/kprobes.c 2006-05-18 13:31:50.000000000 -0700
+++ linux-2.6.17-rc/arch/i386/kernel/kprobes.c 2006-05-31 13:09:26.000000000 -0700
@@ -607,7 +607,7 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
- if (args->regs && user_mode(args->regs))
+ if (args->regs && user_mode_vm(args->regs))
return ret;
switch (val) {
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