* [PATCH] net: print proper warning on dst underflow
@ 2019-09-24 9:09 Jason A. Donenfeld
2019-09-26 7:06 ` David Miller
2019-11-14 0:31 ` Kees Cook
0 siblings, 2 replies; 3+ messages in thread
From: Jason A. Donenfeld @ 2019-09-24 9:09 UTC (permalink / raw)
To: netdev, linux-kernel; +Cc: Jason A. Donenfeld
Proper warnings with stack traces make it much easier to figure out
what's doing the double free and create more meaningful bug reports from
users.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
net/core/dst.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index 1325316d9eab..193af526e908 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -172,7 +172,7 @@ void dst_release(struct dst_entry *dst)
int newrefcnt;
newrefcnt = atomic_dec_return(&dst->__refcnt);
- if (unlikely(newrefcnt < 0))
+ if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
if (!newrefcnt)
@@ -187,7 +187,7 @@ void dst_release_immediate(struct dst_entry *dst)
int newrefcnt;
newrefcnt = atomic_dec_return(&dst->__refcnt);
- if (unlikely(newrefcnt < 0))
+ if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
if (!newrefcnt)
--
2.21.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] net: print proper warning on dst underflow
2019-09-24 9:09 [PATCH] net: print proper warning on dst underflow Jason A. Donenfeld
@ 2019-09-26 7:06 ` David Miller
2019-11-14 0:31 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2019-09-26 7:06 UTC (permalink / raw)
To: Jason; +Cc: netdev, linux-kernel
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 24 Sep 2019 11:09:37 +0200
> Proper warnings with stack traces make it much easier to figure out
> what's doing the double free and create more meaningful bug reports from
> users.
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] net: print proper warning on dst underflow
2019-09-24 9:09 [PATCH] net: print proper warning on dst underflow Jason A. Donenfeld
2019-09-26 7:06 ` David Miller
@ 2019-11-14 0:31 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2019-11-14 0:31 UTC (permalink / raw)
To: Jason A. Donenfeld; +Cc: netdev, linux-kernel
On Tue, Sep 24, 2019 at 11:09:37AM +0200, Jason A. Donenfeld wrote:
> Proper warnings with stack traces make it much easier to figure out
> what's doing the double free and create more meaningful bug reports from
> users.
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> net/core/dst.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/core/dst.c b/net/core/dst.c
> index 1325316d9eab..193af526e908 100644
> --- a/net/core/dst.c
> +++ b/net/core/dst.c
> @@ -172,7 +172,7 @@ void dst_release(struct dst_entry *dst)
> int newrefcnt;
>
> newrefcnt = atomic_dec_return(&dst->__refcnt);
> - if (unlikely(newrefcnt < 0))
> + if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
> net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
> __func__, dst, newrefcnt);
Should __refcnt be a refcount_t to gain saturation protection? It seems
like going negative is bad...
-Kees
> if (!newrefcnt)
> @@ -187,7 +187,7 @@ void dst_release_immediate(struct dst_entry *dst)
> int newrefcnt;
>
> newrefcnt = atomic_dec_return(&dst->__refcnt);
> - if (unlikely(newrefcnt < 0))
> + if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
> net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
> __func__, dst, newrefcnt);
> if (!newrefcnt)
> --
> 2.21.0
>
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-09-26 7:06 ` David Miller
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