From a26cbc650846b74dd7f46dd877fd30c472df14a1 Mon Sep 17 00:00:00 2001 From: Gertjan van Wingerde <gwingerde@kpnplanet.nl> Date: Fri, 6 Jun 2008 22:54:28 +0200 Subject: [PATCH] rt2x00: Fix double usage of skb->cb in USB RX path. It is not safe to use the skb->cb area for both the rxd and skb_frame_desc data at the same time, while they occupy an overlapping piece of memory. This can lead to hard to trace crashes as pointers within skb_frame_desc are pointing into nowhere, or the rxd data is overwritten with non-sense. Fix it by copying the rxd to a small buffer on the stack. Signed-off-by: Gertjan van Wingerde <gwingerde@kpnplanet.nl> Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com> Signed-off-by: John W. Linville <linville@tuxdriver.com> --- drivers/net/wireless/rt2x00/rt2500usb.c | 10 +++------- drivers/net/wireless/rt2x00/rt2x00usb.c | 8 +++----- drivers/net/wireless/rt2x00/rt73usb.c | 10 +++------- 3 files changed, 9 insertions(+), 19 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c index 1bfb68a920a8..9851cefaabf3 100644 --- a/drivers/net/wireless/rt2x00/rt2500usb.c +++ b/drivers/net/wireless/rt2x00/rt2500usb.c @@ -1156,14 +1156,10 @@ static void rt2500usb_fill_rxdone(struct queue_entry *entry, u32 word1; /* - * Copy descriptor to the skb->cb array, this has 2 benefits: - * 1) Each descriptor word is 4 byte aligned. - * 2) Descriptor is safe from moving of frame data in rt2x00usb. + * Copy descriptor to the skbdesc->desc buffer, making it safe from moving of + * frame data in rt2x00usb. */ - skbdesc->desc_len = - min_t(u16, entry->queue->desc_size, sizeof(entry->skb->cb)); - memcpy(entry->skb->cb, rxd, skbdesc->desc_len); - skbdesc->desc = entry->skb->cb; + memcpy(skbdesc->desc, rxd, skbdesc->desc_len); rxd = (__le32 *)skbdesc->desc; /* diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c index 33833bc6d665..68d87f09e054 100644 --- a/drivers/net/wireless/rt2x00/rt2x00usb.c +++ b/drivers/net/wireless/rt2x00/rt2x00usb.c @@ -267,6 +267,7 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) struct sk_buff *skb; struct skb_frame_desc *skbdesc; struct rxdone_entry_desc rxdesc; + u8 rxd[32]; if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags) || !test_and_clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags)) @@ -286,15 +287,12 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) skbdesc = get_skb_frame_desc(entry->skb); memset(skbdesc, 0, sizeof(*skbdesc)); skbdesc->entry = entry; + skbdesc->desc = rxd; + skbdesc->desc_len = entry->queue->desc_size; memset(&rxdesc, 0, sizeof(rxdesc)); rt2x00dev->ops->lib->fill_rxdone(entry, &rxdesc); - /* - * Trim the skb to the correct size. - */ - skb_trim(entry->skb, rxdesc.size); - /* * Allocate a new sk buffer to replace the current one. * If allocation fails, we should drop the current frame diff --git a/drivers/net/wireless/rt2x00/rt73usb.c b/drivers/net/wireless/rt2x00/rt73usb.c index 800a1e278d1e..505a9f5e09e9 100644 --- a/drivers/net/wireless/rt2x00/rt73usb.c +++ b/drivers/net/wireless/rt2x00/rt73usb.c @@ -1428,14 +1428,10 @@ static void rt73usb_fill_rxdone(struct queue_entry *entry, u32 word1; /* - * Copy descriptor to the skb->cb array, this has 2 benefits: - * 1) Each descriptor word is 4 byte aligned. - * 2) Descriptor is safe from moving of frame data in rt2x00usb. + * Copy descriptor to the skbdesc->desc buffer, making it safe from moving of + * frame data in rt2x00usb. */ - skbdesc->desc_len = - min_t(u16, entry->queue->desc_size, sizeof(entry->skb->cb)); - memcpy(entry->skb->cb, rxd, skbdesc->desc_len); - skbdesc->desc = entry->skb->cb; + memcpy(skbdesc->desc, rxd, skbdesc->desc_len); rxd = (__le32 *)skbdesc->desc; /* -- GitLab