In drivers/net/arcnet/arcnet.c, the functions arcnet_reply_tasklet() and
arcnet_send_packet() may be concurrently executed.
arcnet_reply_tasklet()
line 430: dev_kfree_skb(lp->outgoing.skb);
arcnet_send_packet()
line 682: spin_lock_irqsave();
line 690: lp->outgoing.skb = skb;
line 691: proto->prepare_tx(..., skb->len, ...)
Thus, a possible concurrency use-after-free bugs may occur.
To fix this bug, the calls to spin_lock_irqsave() and
spin_unlock_irqrestore() are added in arcnet_reply_tasklet() to protect
dev_kfree_skb(lp->outgoing.skb).
Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/net/arcnet/arcnet.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/net/arcnet/arcnet.c b/drivers/net/arcnet/arcnet.c
index 8459115d9d4e..c5e943d01d66 100644
--- a/drivers/net/arcnet/arcnet.c
+++ b/drivers/net/arcnet/arcnet.c
@@ -426,10 +426,14 @@ static void arcnet_reply_tasklet(unsigned long data)
serr->ee.ee_data = skb_shinfo(skb)->tskey;
serr->ee.ee_info = lp->reply_status;
+ spin_lock_irqsave(&lp->lock, flags);
+
/* finally erasing outgoing skb */
dev_kfree_skb(lp->outgoing.skb);
lp->outgoing.skb = NULL;
+ spin_unlock_irqrestore(&lp->lock, flags);
+
ackskb->dev = lp->dev;
ret = sock_queue_err_skb(sk, ackskb);
--
2.17.0
Hi Jia-Ju,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on net-next/master]
[also build test ERROR on v4.20 next-20181224]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Jia-Ju-Bai/net-arcnet-Fix-a-possible-concurrency-use-after-free-bug-in-arcnet_reply_tasklet/20181227-020417
config: x86_64-randconfig-x005-201851 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All error/warnings (new ones prefixed by >>):
In file included from include/linux/kernel.h:13:0,
from include/linux/list.h:9,
from include/linux/module.h:9,
from drivers/net/arcnet/arcnet.c:46:
drivers/net/arcnet/arcnet.c: In function 'arcnet_reply_tasklet':
>> drivers/net/arcnet/arcnet.c:429:31: error: 'flags' undeclared (first use in this function); did you mean 'class'?
spin_lock_irqsave(&lp->lock, flags);
^
include/linux/typecheck.h:11:9: note: in definition of macro 'typecheck'
typeof(x) __dummy2; \
^
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
>> drivers/net/arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
drivers/net/arcnet/arcnet.c:429:31: note: each undeclared identifier is reported only once for each function it appears in
spin_lock_irqsave(&lp->lock, flags);
^
include/linux/typecheck.h:11:9: note: in definition of macro 'typecheck'
typeof(x) __dummy2; \
^
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
>> drivers/net/arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
>> include/linux/typecheck.h:12:18: warning: comparison of distinct pointer types lacks a cast
(void)(&__dummy == &__dummy2); \
^
>> include/linux/spinlock.h:240:3: note: in expansion of macro 'typecheck'
typecheck(unsigned long, flags); \
^~~~~~~~~
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
>> drivers/net/arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
--
In file included from include/linux/kernel.h:13:0,
from include/linux/list.h:9,
from include/linux/module.h:9,
from drivers/net//arcnet/arcnet.c:46:
drivers/net//arcnet/arcnet.c: In function 'arcnet_reply_tasklet':
drivers/net//arcnet/arcnet.c:429:31: error: 'flags' undeclared (first use in this function); did you mean 'class'?
spin_lock_irqsave(&lp->lock, flags);
^
include/linux/typecheck.h:11:9: note: in definition of macro 'typecheck'
typeof(x) __dummy2; \
^
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
drivers/net//arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
drivers/net//arcnet/arcnet.c:429:31: note: each undeclared identifier is reported only once for each function it appears in
spin_lock_irqsave(&lp->lock, flags);
^
include/linux/typecheck.h:11:9: note: in definition of macro 'typecheck'
typeof(x) __dummy2; \
^
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
drivers/net//arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
>> include/linux/typecheck.h:12:18: warning: comparison of distinct pointer types lacks a cast
(void)(&__dummy == &__dummy2); \
^
>> include/linux/spinlock.h:240:3: note: in expansion of macro 'typecheck'
typecheck(unsigned long, flags); \
^~~~~~~~~
>> include/linux/spinlock.h:359:2: note: in expansion of macro 'raw_spin_lock_irqsave'
raw_spin_lock_irqsave(spinlock_check(lock), flags); \
^~~~~~~~~~~~~~~~~~~~~
drivers/net//arcnet/arcnet.c:429:2: note: in expansion of macro 'spin_lock_irqsave'
spin_lock_irqsave(&lp->lock, flags);
^~~~~~~~~~~~~~~~~
vim +429 drivers/net/arcnet/arcnet.c
395
396 static void arcnet_reply_tasklet(unsigned long data)
397 {
398 struct arcnet_local *lp = (struct arcnet_local *)data;
399
400 struct sk_buff *ackskb, *skb;
401 struct sock_exterr_skb *serr;
402 struct sock *sk;
403 int ret;
404
405 local_irq_disable();
406 skb = lp->outgoing.skb;
407 if (!skb || !skb->sk) {
408 local_irq_enable();
409 return;
410 }
411
412 sock_hold(skb->sk);
413 sk = skb->sk;
414 ackskb = skb_clone_sk(skb);
415 sock_put(skb->sk);
416
417 if (!ackskb) {
418 local_irq_enable();
419 return;
420 }
421
422 serr = SKB_EXT_ERR(ackskb);
423 memset(serr, 0, sizeof(*serr));
424 serr->ee.ee_errno = ENOMSG;
425 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
426 serr->ee.ee_data = skb_shinfo(skb)->tskey;
427 serr->ee.ee_info = lp->reply_status;
428
> 429 spin_lock_irqsave(&lp->lock, flags);
430
431 /* finally erasing outgoing skb */
432 dev_kfree_skb(lp->outgoing.skb);
433 lp->outgoing.skb = NULL;
434
435 spin_unlock_irqrestore(&lp->lock, flags);
436
437 ackskb->dev = lp->dev;
438
439 ret = sock_queue_err_skb(sk, ackskb);
440 if (ret)
441 kfree_skb(ackskb);
442
443 local_irq_enable();
444 };
445
---
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