diff mbox series

[net-next,v1,1/4] virtio-net: fix overflow inside virtnet_rq_alloc

Message ID 20241029084615.91049-2-xuanzhuo@linux.alibaba.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series virtio_net: enable premapped mode by default | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 5 this patch: 5
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 10 of 10 maintainers
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch warning WARNING: line length of 97 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-10-31--09-00 (tests: 779)

Commit Message

Xuan Zhuo Oct. 29, 2024, 8:46 a.m. UTC
When the frag just got a page, then may lead to regression on VM.
Specially if the sysctl net.core.high_order_alloc_disable value is 1,
then the frag always get a page when do refill.

Which could see reliable crashes or scp failure (scp a file 100M in size
to VM).

The issue is that the virtnet_rq_dma takes up 16 bytes at the beginning
of a new frag. When the frag size is larger than PAGE_SIZE,
everything is fine. However, if the frag is only one page and the
total size of the buffer and virtnet_rq_dma is larger than one page, an
overflow may occur.

The commit f9dac92ba908 ("virtio_ring: enable premapped mode whatever
use_dma_api") introduced this problem. And we reverted some commits to
fix this in last linux version. Now we try to enable it and fix this
bug directly.

Here, when the frag size is not enough, we reduce the buffer len to fix
this problem.

Reported-by: "Si-Wei Liu" <si-wei.liu@oracle.com>
Tested-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 792e9eadbfc3..d50c1940eb23 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -926,9 +926,6 @@  static void *virtnet_rq_alloc(struct receive_queue *rq, u32 size, gfp_t gfp)
 	void *buf, *head;
 	dma_addr_t addr;
 
-	if (unlikely(!skb_page_frag_refill(size, alloc_frag, gfp)))
-		return NULL;
-
 	head = page_address(alloc_frag->page);
 
 	if (rq->do_dma) {
@@ -2423,6 +2420,9 @@  static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
 	len = SKB_DATA_ALIGN(len) +
 	      SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
+	if (unlikely(!skb_page_frag_refill(len, &rq->alloc_frag, gfp)))
+		return -ENOMEM;
+
 	buf = virtnet_rq_alloc(rq, len, gfp);
 	if (unlikely(!buf))
 		return -ENOMEM;
@@ -2525,6 +2525,12 @@  static int add_recvbuf_mergeable(struct virtnet_info *vi,
 	 */
 	len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);
 
+	if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
+		return -ENOMEM;
+
+	if (!alloc_frag->offset && len + room + sizeof(struct virtnet_rq_dma) > alloc_frag->size)
+		len -= sizeof(struct virtnet_rq_dma);
+
 	buf = virtnet_rq_alloc(rq, len + room, gfp);
 	if (unlikely(!buf))
 		return -ENOMEM;