From 18fa11efc279c20af5eefff2bbe814ca067e51ae Mon Sep 17 00:00:00 2001 From: Chris Leech Date: Tue, 3 Nov 2009 11:50:05 -0800 Subject: [PATCH] [SCSI] libfc, fcoe: fixes for highmem skb linearize panics There are cases outside of our control that may result in a transmit skb being linearized in dev_queue_xmit. There are a couple of bugs in libfc/fcoe that can result in a panic at that point. This patch contains two fixes to prevent those panics. 1) use fast cloning instead of shared skbs with dev_queue_xmit dev_queue_xmit doen't want shared skbuffs being passed in, and __skb_linearize will BUG if the skb is shared. FCoE is holding an extra reference around the call to dev_queue_xmit, so that when it returns an error code indicating the frame has been dropped it can maintain it's own backlog and retransmit. Switch to using fast skb cloning for this instead. 2) don't append compound pages as > PAGE_SIZE skb fragments fc_fcp_send_data will append pages from a scatterlist to the nr_frags[] if the netdev supports it. But, it's using > PAGE_SIZE compound pages as a single skb_frag. In the highmem linearize case that page will be passed to kmap_atomic to get a mapping to copy out of, but kmap_atomic will only allow access to the first PAGE_SIZE part. The memcpy will keep going and cause a page fault once is crosses the first boundary. If fc_fcp_send_data uses linear buffers from the start, it calls kmap_atomic one PAGE_SIZE at a time. That same logic needs to be applied when setting up skb_frags. Signed-off-by: Chris Leech Signed-off-by: Robert Love Signed-off-by: James Bottomley --- drivers/scsi/fcoe/fcoe.c | 5 +++-- drivers/scsi/libfc/fc_fcp.c | 20 ++++++++++---------- drivers/scsi/libfc/fc_frame.c | 5 +++-- 3 files changed, 16 insertions(+), 14 deletions(-) diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index 28029a342892..b570f39faa3a 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -1267,10 +1267,11 @@ err2: */ static inline int fcoe_start_io(struct sk_buff *skb) { + struct sk_buff *nskb; int rc; - skb_get(skb); - rc = dev_queue_xmit(skb); + nskb = skb_clone(skb, GFP_ATOMIC); + rc = dev_queue_xmit(nskb); if (rc != 0) return rc; kfree_skb(skb); diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c index db252e2722d0..c4b58d042f6f 100644 --- a/drivers/scsi/libfc/fc_fcp.c +++ b/drivers/scsi/libfc/fc_fcp.c @@ -530,11 +530,13 @@ static int fc_fcp_send_data(struct fc_fcp_pkt *fsp, struct fc_seq *seq, struct scatterlist *sg; struct fc_frame *fp = NULL; struct fc_lport *lport = fsp->lp; + struct page *page; size_t remaining; size_t t_blen; size_t tlen; size_t sg_bytes; size_t frame_offset, fh_parm_offset; + size_t off; int error; void *data = NULL; void *page_addr; @@ -605,28 +607,26 @@ static int fc_fcp_send_data(struct fc_fcp_pkt *fsp, struct fc_seq *seq, fh_parm_offset = frame_offset; fr_max_payload(fp) = fsp->max_payload; } + + off = offset + sg->offset; sg_bytes = min(tlen, sg->length - offset); + sg_bytes = min(sg_bytes, + (size_t) (PAGE_SIZE - (off & ~PAGE_MASK))); + page = sg_page(sg) + (off >> PAGE_SHIFT); if (using_sg) { - get_page(sg_page(sg)); + get_page(page); skb_fill_page_desc(fp_skb(fp), skb_shinfo(fp_skb(fp))->nr_frags, - sg_page(sg), sg->offset + offset, - sg_bytes); + page, off & ~PAGE_MASK, sg_bytes); fp_skb(fp)->data_len += sg_bytes; fr_len(fp) += sg_bytes; fp_skb(fp)->truesize += PAGE_SIZE; } else { - size_t off = offset + sg->offset; - /* * The scatterlist item may be bigger than PAGE_SIZE, * but we must not cross pages inside the kmap. */ - sg_bytes = min(sg_bytes, (size_t) (PAGE_SIZE - - (off & ~PAGE_MASK))); - page_addr = kmap_atomic(sg_page(sg) + - (off >> PAGE_SHIFT), - KM_SOFTIRQ0); + page_addr = kmap_atomic(page, KM_SOFTIRQ0); memcpy(data, (char *)page_addr + (off & ~PAGE_MASK), sg_bytes); kunmap_atomic(page_addr, KM_SOFTIRQ0); diff --git a/drivers/scsi/libfc/fc_frame.c b/drivers/scsi/libfc/fc_frame.c index 79c956501bd9..6da01c616964 100644 --- a/drivers/scsi/libfc/fc_frame.c +++ b/drivers/scsi/libfc/fc_frame.c @@ -58,12 +58,13 @@ struct fc_frame *_fc_frame_alloc(size_t len) WARN_ON((len % sizeof(u32)) != 0); len += sizeof(struct fc_frame_header); - skb = dev_alloc_skb(len + FC_FRAME_HEADROOM + FC_FRAME_TAILROOM); + skb = alloc_skb_fclone(len + FC_FRAME_HEADROOM + FC_FRAME_TAILROOM + + NET_SKB_PAD, GFP_ATOMIC); if (!skb) return NULL; + skb_reserve(skb, NET_SKB_PAD + FC_FRAME_HEADROOM); fp = (struct fc_frame *) skb; fc_frame_init(fp); - skb_reserve(skb, FC_FRAME_HEADROOM); skb_put(skb, len); return fp; } -- 2.20.1