4 files changed, 24 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 9e9a70e50c72..fba8dfeda67c 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -625,6 +625,14 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         unlazy_fpu(prev_p);
         write_pda(kernelstack,
                   task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
+#ifdef CONFIG_CC_STACKPROTECTOR
+        write_pda(stack_canary, next_p->stack_canary);
+        /*
+         * Build time only check to make sure the stack_canary is at
+         * offset 40 in the pda; this is a gcc ABI requirement
+         */
+        BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
+#endif
 
         /*
          * Now maybe reload the debug registers and handle I/O bitmaps
diff --git a/include/asm-x86_64/pda.h b/include/asm-x86_64/pda.h
index 6794ffaae433..e7773e0af865 100644
--- a/include/asm-x86_64/pda.h
+++ b/include/asm-x86_64/pda.h
@@ -16,7 +16,12 @@ struct x8664_pda {
         unsigned long oldrsp;       /* 24 user rsp for system call */
         int irqcount;               /* 32 Irq nesting counter. Starts with -1 */
         int cpunumber;              /* 36 Logical CPU number */
-        char *irqstackptr;      /* 40 top of irqstack */
+#ifdef CONFIG_CC_STACKPROTECTOR
+        unsigned long stack_canary;     /* 40 stack canary value */
+                                        /* gcc-ABI: this canary MUST be at
+                                           offset 40!!! */
+#endif
+        char *irqstackptr;
         int nodenumber;             /* number of current node */
         unsigned int __softirq_pending;
         unsigned int __nmi_count;       /* number of NMI on this CPUs */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 807556c5bcd2..9d4aa7f95bc8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -819,6 +819,11 @@ struct task_struct {
         unsigned did_exec:1;
         pid_t pid;
         pid_t tgid;
+
+#ifdef CONFIG_CC_STACKPROTECTOR
+        /* Canary value for the -fstack-protector gcc feature */
+        unsigned long stack_canary;
+#endif
         /* 
          * pointers to (original) parent process, youngest child, younger sibling,
          * older sibling, respectively.  (p->father can be replaced with 
diff --git a/kernel/fork.c b/kernel/fork.c
index f9b014e3e700..a0dad84567c9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -45,6 +45,7 @@
 #include <linux/cn_proc.h>
 #include <linux/delayacct.h>
 #include <linux/taskstats_kern.h>
+#include <linux/random.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -175,6 +176,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
         tsk->thread_info = ti;
         setup_thread_stack(tsk, orig);
 
+#ifdef CONFIG_CC_STACKPROTECTOR
+        tsk->stack_canary = get_random_int();
+#endif
+
         /* One for us, one for whoever does the "release_task()" (usually parent) */
         atomic_set(&tsk->usage,2);
         atomic_set(&tsk->fs_excl, 0);