From: Eric Dumazet <eric.dumazet@gmail.com>

Date: Tue, 23 Nov 2010 14:09:15 +0000 (+0000)

Subject: scm: lower SCM_MAX_FD

X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fdavem%2Fnet-next-2.6.git;a=commitdiff_plain;h=bba14de98753cb6599a2dae0e520714b2153522d

scm: lower SCM_MAX_FD

Lower SCM_MAX_FD from 255 to 253 so that allocations for scm_fp_list are

halved. (commit f8d570a4 added two pointers in this structure)

scm_fp_dup() should not copy whole structure (and trigger kmemcheck

warnings), but only the used part. While we are at it, only allocate

needed size.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

---

diff --git a/include/net/scm.h b/include/net/scm.h

index 3165650..745460f 100644

--- a/include/net/scm.h

+++ b/include/net/scm.h

@@ -10,11 +10,12 @@

 /* Well, we should have at least one descriptor open

  * to accept passed FDs 8)

  */

-#define SCM_MAX_FD	255

+#define SCM_MAX_FD	253

 struct scm_fp_list {

 	struct list_head	list;

-	int			count;

+	short			count;

+	short			max;

 	struct file		*fp[SCM_MAX_FD];

 };

diff --git a/net/core/scm.c b/net/core/scm.c

index 413cab8..bbe4544 100644

--- a/net/core/scm.c

+++ b/net/core/scm.c

@@ -79,10 +79,11 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)

 			return -ENOMEM;

 		*fplp = fpl;

 		fpl->count = 0;

+		fpl->max = SCM_MAX_FD;

 	}

 	fpp = &fpl->fp[fpl->count];

-	if (fpl->count + num > SCM_MAX_FD)

+	if (fpl->count + num > fpl->max)

 		return -EINVAL;

 	/*

@@ -331,11 +332,12 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)

 	if (!fpl)

 		return NULL;

-	new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);

+	new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),

+			  GFP_KERNEL);

 	if (new_fpl) {

-		for (i=fpl->count-1; i>=0; i--)

+		for (i = 0; i < fpl->count; i++)

 			get_file(fpl->fp[i]);

-		memcpy(new_fpl, fpl, sizeof(*fpl));

+		new_fpl->max = new_fpl->count;

 	}

 	return new_fpl;

 }