OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

net: fix up truesize of cloned skb in skb_prepare_for_shift() 

commit 097b9146c0e26aabaa6ff3e5ea536a53f5254a79 upstream.

Avoid the assumption that ksize(kmalloc(S)) == ksize(kmalloc(S)): when
cloning an skb, save and restore truesize after pskb_expand_head(). This
can occur if the allocator decides to service an allocation of the same
size differently (e.g. use a different size class, or pass the
allocation on to KFENCE).

Because truesize is used for bookkeeping (such as sk_wmem_queued), a
modified truesize of a cloned skb may result in corrupt bookkeeping and
relevant warnings (such as in sk_stream_kill_queues()).

Link: https://lkml.kernel.org/r/X9JR/J6dMMOy1obu@elver.google.com
Reported-by: syzbot+7b99aafdcc2eedea6178@syzkaller.appspotmail.com
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210201160420.2826895-1-elver@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Marco Elver 2021-02-01 17:04:20 +01:00 committed by Greg Kroah-Hartman
parent 4ceb5ca9e6
commit e6af7cb64b
1 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
net/core/skbuff.c
View File

@ -3290,7 +3290,19 @@ EXPORT_SYMBOL(skb_split);
*/
static int skb_prepare_for_shift(struct sk_buff *skb)
{
return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
int ret = 0;
if (skb_cloned(skb)) {
/* Save and restore truesize: pskb_expand_head() may reallocate
* memory where ksize(kmalloc(S)) != ksize(kmalloc(S)), but we
* cannot change truesize at this point.
*/
unsigned int save_truesize = skb->truesize;
ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
skb->truesize = save_truesize;
}
return ret;
}
/**