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authorVasily Gorbik <gor@linux.ibm.com>2019-08-13 21:11:08 +0300
committerVasily Gorbik <gor@linux.ibm.com>2019-08-21 13:58:52 +0300
commit8769f610fe6d473e5e8e221709c3ac402037da6c (patch)
treec740258be7d3cd1f37d7c58d4495d7b11af31ce9 /arch/s390/kernel/process.c
parentf45f7b5bdaa4828ce871cf03f7c01599a0de57a5 (diff)
downloadlinux-8769f610fe6d473e5e8e221709c3ac402037da6c.tar.xz
s390/process: avoid potential reading of freed stack
With THREAD_INFO_IN_TASK (which is selected on s390) task's stack usage is refcounted and should always be protected by get/put when touching other task's stack to avoid race conditions with task's destruction code. Fixes: d5c352cdd022 ("s390: move thread_info into task_struct") Cc: stable@vger.kernel.org # v4.10+ Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/process.c')
-rw-r--r--arch/s390/kernel/process.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 63873aa6693f..9f2727bf3cbe 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -184,20 +184,30 @@ unsigned long get_wchan(struct task_struct *p)
if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
return 0;
+
+ if (!try_get_task_stack(p))
+ return 0;
+
low = task_stack_page(p);
high = (struct stack_frame *) task_pt_regs(p);
sf = (struct stack_frame *) p->thread.ksp;
- if (sf <= low || sf > high)
- return 0;
+ if (sf <= low || sf > high) {
+ return_address = 0;
+ goto out;
+ }
for (count = 0; count < 16; count++) {
sf = (struct stack_frame *) sf->back_chain;
- if (sf <= low || sf > high)
- return 0;
+ if (sf <= low || sf > high) {
+ return_address = 0;
+ goto out;
+ }
return_address = sf->gprs[8];
if (!in_sched_functions(return_address))
- return return_address;
+ goto out;
}
- return 0;
+out:
+ put_task_stack(p);
+ return return_address;
}
unsigned long arch_align_stack(unsigned long sp)