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authorRusty Russell <rusty@rustcorp.com.au>2009-04-19 23:14:00 -0600
committerRusty Russell <rusty@rustcorp.com.au>2009-04-19 23:14:01 +0930
commita489f0b555b753f9df8ddc24c7e74f657ef7ee7b (patch)
tree560bd8c56524b658eb0b46e03ef42e262eb5f9b7 /drivers/lguest
parent88df781afb788fa588dbf2e77f205214022a8893 (diff)
lguest: fix guest crash on non-linear addresses in gdt pvops
Fixes guest crash 'lguest: bad read address 0x4800000 len 256' The new per-cpu allocator ends up handing a non-linear address to write_gdt_entry. We do __pa() on it, and hand it to the host, which kills us. I've long wanted to make the hypercall "LOAD_GDT_ENTRY" to match the IDT code, but had no pressing reason until now. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: lguest@ozlabs.org
Diffstat (limited to 'drivers/lguest')
-rw-r--r--drivers/lguest/lg.h3
-rw-r--r--drivers/lguest/segments.c13
-rw-r--r--drivers/lguest/x86/core.c4
3 files changed, 11 insertions, 9 deletions
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index ac8a4a3741b..af92a176697 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -158,7 +158,8 @@ void free_interrupts(void);
/* segments.c: */
void setup_default_gdt_entries(struct lguest_ro_state *state);
void setup_guest_gdt(struct lg_cpu *cpu);
-void load_guest_gdt(struct lg_cpu *cpu, unsigned long table, u32 num);
+void load_guest_gdt_entry(struct lg_cpu *cpu, unsigned int i,
+ u32 low, u32 hi);
void guest_load_tls(struct lg_cpu *cpu, unsigned long tls_array);
void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt);
void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt);
diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
index 4f15439b7f1..7ede64ffeef 100644
--- a/drivers/lguest/segments.c
+++ b/drivers/lguest/segments.c
@@ -144,18 +144,19 @@ void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt)
gdt[i] = cpu->arch.gdt[i];
}
-/*H:620 This is where the Guest asks us to load a new GDT (LHCALL_LOAD_GDT).
- * We copy it from the Guest and tweak the entries. */
-void load_guest_gdt(struct lg_cpu *cpu, unsigned long table, u32 num)
+/*H:620 This is where the Guest asks us to load a new GDT entry
+ * (LHCALL_LOAD_GDT_ENTRY). We tweak the entry and copy it in. */
+void load_guest_gdt_entry(struct lg_cpu *cpu, u32 num, u32 lo, u32 hi)
{
/* We assume the Guest has the same number of GDT entries as the
* Host, otherwise we'd have to dynamically allocate the Guest GDT. */
if (num > ARRAY_SIZE(cpu->arch.gdt))
kill_guest(cpu, "too many gdt entries %i", num);
- /* We read the whole thing in, then fix it up. */
- __lgread(cpu, cpu->arch.gdt, table, num * sizeof(cpu->arch.gdt[0]));
- fixup_gdt_table(cpu, 0, ARRAY_SIZE(cpu->arch.gdt));
+ /* Set it up, then fix it. */
+ cpu->arch.gdt[num].a = lo;
+ cpu->arch.gdt[num].b = hi;
+ fixup_gdt_table(cpu, num, num+1);
/* Mark that the GDT changed so the core knows it has to copy it again,
* even if the Guest is run on the same CPU. */
cpu->changed |= CHANGED_GDT;
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index d6d7ac0982a..1a83910f674 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -568,8 +568,8 @@ void __exit lguest_arch_host_fini(void)
int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
{
switch (args->arg0) {
- case LHCALL_LOAD_GDT:
- load_guest_gdt(cpu, args->arg1, args->arg2);
+ case LHCALL_LOAD_GDT_ENTRY:
+ load_guest_gdt_entry(cpu, args->arg1, args->arg2, args->arg3);
break;
case LHCALL_LOAD_IDT_ENTRY:
load_guest_idt_entry(cpu, args->arg1, args->arg2, args->arg3);