The patch titled
i386: Fix machine_check entry point in entry.S to not dereference kernel memory from user space context
has been removed from the -mm tree. Its filename was
i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context.patch
This patch was dropped because it was nacked by the maintainer
------------------------------------------------------
Subject: i386: Fix machine_check entry point in entry.S to not dereference kernel memory from user space context
From: Neil Horman <nhorman@xxxxxxxxxxxxx>
It appears that when the i386 arch traps on a machine check, the code in
entry.S loads the vector pointed to by the machine_check_vector kernel
varialbe. Since this happens before the switch to the kernel context in
error_code, the result is an oops, if the reverenced address is unmapped,
or silent memory corruption if the address is mapped.
This patch corrects that, by jumping instead to a statically allocated
kernel function instead, allowing us to load a static value, rather than
the contents of a memory address before the switch to kernel context, like
all of our other entry points do.
Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/cpu/mcheck/mce.c | 5 +++++
arch/i386/kernel/cpu/mcheck/mce.h | 1 +
arch/i386/kernel/entry.S | 2 +-
3 files changed, 7 insertions(+), 1 deletion(-)
diff -puN arch/i386/kernel/cpu/mcheck/mce.c~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context arch/i386/kernel/cpu/mcheck/mce.c
--- a/arch/i386/kernel/cpu/mcheck/mce.c~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context
+++ a/arch/i386/kernel/cpu/mcheck/mce.c
@@ -29,6 +29,11 @@ static fastcall void unexpected_machine_
/* Call the installed machine check handler for this CPU setup. */
void fastcall (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check;
+asmlinkage void do_machine_check(struct pt_regs *regs, long error_code)
+{
+ machine_check_vector(regs, error_code);
+}
+
/* This has to be run for each processor */
void mcheck_init(struct cpuinfo_x86 *c)
{
diff -puN arch/i386/kernel/cpu/mcheck/mce.h~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context arch/i386/kernel/cpu/mcheck/mce.h
--- a/arch/i386/kernel/cpu/mcheck/mce.h~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context
+++ a/arch/i386/kernel/cpu/mcheck/mce.h
@@ -8,6 +8,7 @@ void winchip_mcheck_init(struct cpuinfo_
/* Call the installed machine check handler for this CPU setup. */
extern fastcall void (*machine_check_vector)(struct pt_regs *, long error_code);
+extern asmlinkage void do_machine_check(struct pt_regs *, long error_code);
extern int mce_disabled;
extern int nr_mce_banks;
diff -puN arch/i386/kernel/entry.S~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context arch/i386/kernel/entry.S
--- a/arch/i386/kernel/entry.S~i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context
+++ a/arch/i386/kernel/entry.S
@@ -964,7 +964,7 @@ ENTRY(machine_check)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
- pushl machine_check_vector
+ pushl $do_machine_check
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
_
Patches currently in -mm which might be from nhorman@xxxxxxxxxxxxx are
i386-fix-machine_check-entry-point-in-entrys-to-not-dereference-kernel-memory-from-user-space-context.patch
correct-misc_register-return-code-handling-in-several-drivers.patch
-
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