Re: [Bug #15196] kmem_cache_create: duplicate cache ccid2_h

[Xiaotian Feng <xtfeng-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, Feb 1, 2010 at 8:22 AM, Rafael J. Wysocki <rjw-KKrjLPT3xs0@public.gmane.org> wrote:
> This message has been generated automatically as a part of a report
> of recent regressions.
>
> The following bug entry is on the current list of known regressions
> from 2.6.32.  Please verify if it still should be listed and let me know
> (either way).
>
>
> Bug-Entry       : http://bugzilla.kernel.org/show_bug.cgi?id=15196
> Subject         : kmem_cache_create: duplicate cache ccid2_h
> Submitter       : Heinz Diehl <htd-HjJ2MNWy62to6+H+lsi3Gti2O/JbrIOy@public.gmane.org>
> Date            : 2010-01-30 18:33 (2 days old)
> References      : http://marc.info/?l=linux-kernel&m=126487640324942&w=4

Cced Neil,

I think this one is introduced by commit
de4ef86cfce60d2250111f34f8a084e769f23b16,
passing char *slab_name_fmt as function parameter, but vsnprintf is
using sizeof(slab_name_fmt),
which is 8 (or 4 in 32bit kernel) instead of 32 as old version.

Does following patch resolve this bug, Heinz?

diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
index 57dfb9c..6e52879 100644
--- a/net/dccp/ccid.c
+++ b/net/dccp/ccid.c
@@ -77,13 +77,14 @@ int ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
        return err;
 }

-static struct kmem_cache *ccid_kmem_cache_create(int obj_size, char
*slab_name_fmt, const char *fmt,...)
+static struct kmem_cache *ccid_kmem_cache_create(int obj_size, char
*slab_name_fmt,
+                                                int length,const char *fmt,...)
 {
        struct kmem_cache *slab;
        va_list args;

        va_start(args, fmt);
-       vsnprintf(slab_name_fmt, sizeof(slab_name_fmt), fmt, args);
+       vsnprintf(slab_name_fmt, length, fmt, args);
        va_end(args);

        slab = kmem_cache_create(slab_name_fmt, sizeof(struct ccid) +
obj_size, 0,
@@ -104,6 +105,7 @@ static int ccid_activate(struct ccid_operations *ccid_ops)
        ccid_ops->ccid_hc_rx_slab =
                        ccid_kmem_cache_create(ccid_ops->ccid_hc_rx_obj_size,
                                               ccid_ops->ccid_hc_rx_slab_name,
+
sizeof(ccid_ops->ccid_hc_rx_slab_name),
                                               "ccid%u_hc_rx_sock",
                                               ccid_ops->ccid_id);
        if (ccid_ops->ccid_hc_rx_slab == NULL)
@@ -112,6 +114,7 @@ static int ccid_activate(struct ccid_operations *ccid_ops)
        ccid_ops->ccid_hc_tx_slab =
                        ccid_kmem_cache_create(ccid_ops->ccid_hc_tx_obj_size,
                                               ccid_ops->ccid_hc_tx_slab_name,
+
sizeof(ccid_ops->ccid_hc_tx_slab_name),
                                               "ccid%u_hc_tx_sock",
                                               ccid_ops->ccid_id);
        if (ccid_ops->ccid_hc_tx_slab == NULL)

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