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coda: convert from atomic_t to refcount_t on coda_vm_ops->refcnt

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refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.

Link: https://lkml.kernel.org/r/20210908140308.18491-8-jaharkes@cs.cmu.edu
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Jing Yangyang <jing.yangyang@zte.com.cn>
Cc: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xiyu Yang 2021-11-08 18:34:48 -08:00 committed by Linus Torvalds
parent 5a646fb3a3
commit 1077c28577
1 changed files with 5 additions and 4 deletions
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9
fs/coda/file.c
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@ -8,6 +8,7 @@
* to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
*/
#include <linux/refcount.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>
@ -28,7 +29,7 @@
#include "coda_int.h"
struct coda_vm_ops {
atomic_t refcnt;
refcount_t refcnt;
struct file *coda_file;
const struct vm_operations_struct *host_vm_ops;
struct vm_operations_struct vm_ops;
@ -98,7 +99,7 @@ coda_vm_open(struct vm_area_struct *vma)
struct coda_vm_ops *cvm_ops =
container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
atomic_inc(&cvm_ops->refcnt);
refcount_inc(&cvm_ops->refcnt);
if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
cvm_ops->host_vm_ops->open(vma);
@ -113,7 +114,7 @@ coda_vm_close(struct vm_area_struct *vma)
if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
cvm_ops->host_vm_ops->close(vma);
if (atomic_dec_and_test(&cvm_ops->refcnt)) {
if (refcount_dec_and_test(&cvm_ops->refcnt)) {
vma->vm_ops = cvm_ops->host_vm_ops;
fput(cvm_ops->coda_file);
kfree(cvm_ops);
@ -189,7 +190,7 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
cvm_ops->vm_ops.open = coda_vm_open;
cvm_ops->vm_ops.close = coda_vm_close;
cvm_ops->coda_file = coda_file;
atomic_set(&cvm_ops->refcnt, 1);
refcount_set(&cvm_ops->refcnt, 1);
vma->vm_ops = &cvm_ops->vm_ops;
}