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[PATCH] Add the canary field to the PDA area and the task struct 

This patch adds the per thread cookie field to the task struct and the PDA.
Also it makes sure that the PDA value gets the new cookie value at context
switch, and that a new task gets a new cookie at task creation time.

Signed-off-by: Arjan van Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andi Kleen <ak@suse.de>
CC: Andi Kleen <ak@suse.de>
This commit is contained in:
Arjan van de Ven 2006-09-26 10:52:38 +02:00 committed by Andi Kleen
parent b62a5c740d
commit 0a42540580
4 changed files with 24 additions and 1 deletions
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8
arch/x86_64/kernel/process.c
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@ -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

7
include/asm-x86_64/pda.h
View File

@ -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 */

5
include/linux/sched.h
View File

@ -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

5
kernel/fork.c
View File

@ -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);