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Subject[ 50/50] x86: avoid remapping data in parse_setup_data()
Date
3.11-stable review patch.  If anyone has any objections, please let me know.

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

From: Linn Crosetto <linn@hp.com>

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>

---
arch/x86/include/asm/e820.h | 2 +-
arch/x86/kernel/e820.c | 5 ++++-
arch/x86/kernel/setup.c | 19 ++++++++-----------
3 files changed, 13 insertions(+), 13 deletions(-)

--- 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))
--- 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");
}
--- 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;
}
}




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