x86: avoid remapping data in parse_setup_data()

commit 30e46b574a1db7d14404e52dca8e1aa5f5155fd2 upstream.

Type SETUP_PCI, added by setup_efi_pci(), may advertise a ROM size
larger than early_memremap() is able to handle, which is currently
limited to 256kB. If this occurs it leads to a NULL dereference in
parse_setup_data().

To avoid this, remap the setup_data header and allow parsing functions
for individual types to handle their own data remapping.

Signed-off-by: Linn Crosetto <linn@hp.com>
Link: http://lkml.kernel.org/r/1376430401-67445-1-git-send-email-linn@hp.com
Acked-by: Yinghai Lu <yinghai@kernel.org>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 13 insertions, 13 deletions

diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index cccd07fa5e3a..779c2efe2e97 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -29,7 +29,7 @@ extern void e820_setup_gap(void);
 extern int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
                         unsigned long start_addr, unsigned long long end_addr);
 struct setup_data;
-extern void parse_e820_ext(struct setup_data *data);
+extern void parse_e820_ext(u64 phys_addr, u32 data_len);
 
 #if defined(CONFIG_X86_64) || \
         (defined(CONFIG_X86_32) && defined(CONFIG_HIBERNATION))
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index d32abeabbda5..174da5fc5a7b 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -658,15 +658,18 @@ __init void e820_setup_gap(void)
  * boot_params.e820_map, others are passed via SETUP_E820_EXT node of
  * linked list of struct setup_data, which is parsed here.
  */
-void __init parse_e820_ext(struct setup_data *sdata)
+void __init parse_e820_ext(u64 phys_addr, u32 data_len)
 {
         int entries;
         struct e820entry *extmap;
+        struct setup_data *sdata;
 
+        sdata = early_memremap(phys_addr, data_len);
         entries = sdata->len / sizeof(struct e820entry);
         extmap = (struct e820entry *)(sdata->data);
         __append_e820_map(extmap, entries);
         sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
+        early_iounmap(sdata, data_len);
         printk(KERN_INFO "e820: extended physical RAM map:\n");
         e820_print_map("extended");
 }
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 56f7fcfe7fa2..91964c663f0d 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -426,25 +426,23 @@ static void __init reserve_initrd(void)
 static void __init parse_setup_data(void)
 {
         struct setup_data *data;
-        u64 pa_data;
+        u64 pa_data, pa_next;
 
         pa_data = boot_params.hdr.setup_data;
         while (pa_data) {
-                u32 data_len, map_len;
+                u32 data_len, map_len, data_type;
 
                 map_len = max(PAGE_SIZE - (pa_data & ~PAGE_MASK),
                               (u64)sizeof(struct setup_data));
                 data = early_memremap(pa_data, map_len);
                 data_len = data->len + sizeof(struct setup_data);
-                if (data_len > map_len) {
-                        early_iounmap(data, map_len);
-                        data = early_memremap(pa_data, data_len);
-                        map_len = data_len;
-                }
+                data_type = data->type;
+                pa_next = data->next;
+                early_iounmap(data, map_len);
 
-                switch (data->type) {
+                switch (data_type) {
                 case SETUP_E820_EXT:
-                        parse_e820_ext(data);
+                        parse_e820_ext(pa_data, data_len);
                         break;
                 case SETUP_DTB:
                         add_dtb(pa_data);
@@ -452,8 +450,7 @@ static void __init parse_setup_data(void)
                 default:
                         break;
                 }
-                pa_data = data->next;
-                early_iounmap(data, map_len);
+                pa_data = pa_next;
         }
 }