xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[NET]: Fix incorrect sg_mark_end() calls.

Browse Source 
This fixes scatterlist corruptions added by

	commit 68e3f5dd4d
	[CRYPTO] users: Fix up scatterlist conversion errors

The issue is that the code calls sg_mark_end() which clobbers the
sg_page() pointer of the final scatterlist entry.

The first part fo the fix makes skb_to_sgvec() do __sg_mark_end().

After considering all skb_to_sgvec() call sites the most correct
solution is to call __sg_mark_end() in skb_to_sgvec() since that is
what all of the callers would end up doing anyways.

I suspect this might have fixed some problems in virtio_net which is
the sole non-crypto user of skb_to_sgvec().

Other similar sg_mark_end() cases were converted over to
__sg_mark_end() as well.

Arguably sg_mark_end() is a poorly named function because it doesn't
just "mark", it clears out the page pointer as a side effect, which is
what led to these bugs in the first place.

The one remaining plain sg_mark_end() call is in scsi_alloc_sgtable()
and arguably it could be converted to __sg_mark_end() if only so that
we can delete this confusing interface from linux/scatterlist.h

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2007-10-30 21:29:29 -07:00
parent 07afa04025
commit 51c739d1f4
7 changed files with 37 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
net/core/skbuff.c
View File

@@ -2028,8 +2028,8 @@ void __init skb_init(void)
* Fill the specified scatter-gather list with mappings/pointers into a
* region of the buffer space attached to a socket buffer.
*/
int
skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
static int
__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
@@ -2078,7 +2078,8 @@ skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
elt += __skb_to_sgvec(list, sg+elt, offset - start,
copy);
if ((len -= copy) == 0)
return elt;
offset += copy;
@@ -2090,6 +2091,15 @@ skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
return elt;
}
int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
{
int nsg = __skb_to_sgvec(skb, sg, offset, len);
__sg_mark_end(&sg[nsg - 1]);
return nsg;
}
/**
* skb_cow_data - Check that a socket buffer's data buffers are writable
* @skb: The socket buffer to check.