Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:

 - Expand the space for uncompressing as the LZ4 worst case does not fit
   into the currently reserved space

 - Validate boot parameters more strictly to prevent out of bound access
   in the decompressor/boot code

 - Fix off by one errors in get_segment_base()

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Prevent faulty bootparams.screeninfo from causing harm
  x86/boot: Provide more slack space during decompression
  x86/ldt: Fix off by one in get_segment_base()

3 files changed, 10 insertions, 8 deletions

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index a0838ab929f2..c14217cd0155 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -116,8 +116,7 @@ void __putstr(const char *s)
                 }
         }
 
-        if (boot_params->screen_info.orig_video_mode == 0 &&
-            lines == 0 && cols == 0)
+        if (lines == 0 || cols == 0)
                 return;
 
         x = boot_params->screen_info.orig_x;
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 2ed8f0c25def..1bb08ecffd24 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -520,8 +520,14 @@ pref_address:		.quad LOAD_PHYSICAL_ADDR	# preferred load addr
 # the description in lib/decompressor_xxx.c for specific information.
 #
 # extra_bytes = (uncompressed_size >> 12) + 65536 + 128
+#
+# LZ4 is even worse: data that cannot be further compressed grows by 0.4%,
+# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as
+# the size-dependent part now grows so fast.
+#
+# extra_bytes = (uncompressed_size >> 8) + 65536
 
-#define ZO_z_extra_bytes        ((ZO_z_output_len >> 12) + 65536 + 128)
+#define ZO_z_extra_bytes        ((ZO_z_output_len >> 8) + 65536)
 #if ZO_z_output_len > ZO_z_input_len
 # define ZO_z_extract_offset    (ZO_z_output_len + ZO_z_extra_bytes - \
                                  ZO_z_input_len)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index af12e294caed..939050169d12 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2335,12 +2335,9 @@ static unsigned long get_segment_base(unsigned int segment)
 #ifdef CONFIG_MODIFY_LDT_SYSCALL
                 struct ldt_struct *ldt;
 
-                if (idx > LDT_ENTRIES)
-                        return 0;
-
                 /* IRQs are off, so this synchronizes with smp_store_release */
                 ldt = lockless_dereference(current->active_mm->context.ldt);
-                if (!ldt || idx > ldt->nr_entries)
+                if (!ldt || idx >= ldt->nr_entries)
                         return 0;
 
                 desc = &ldt->entries[idx];
@@ -2348,7 +2345,7 @@ static unsigned long get_segment_base(unsigned int segment)
                 return 0;
 #endif
         } else {
-                if (idx > GDT_ENTRIES)
+                if (idx >= GDT_ENTRIES)
                         return 0;
 
                 desc = raw_cpu_ptr(gdt_page.gdt) + idx;