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* [dpdk-dev] [PATCH v2] gso: fix pyld_unit_size issue for udp gso
@ 2020-09-17  2:12 yang_y_yi
  2020-09-17  2:16 ` Hu, Jiayu
  0 siblings, 1 reply; 3+ messages in thread
From: yang_y_yi @ 2020-09-17  2:12 UTC (permalink / raw)
  To: dev; +Cc: jiayu.hu, thomas, yangyi01, yang_y_yi

From: Yi Yang <yangyi01@inspur.com>

Fragment offset of IPv4 header is measured in units of
8 bytes. Fragment offset of UDP fragments will be wrong
after GSO if pyld_unit_size isn't multiple of 8. Say
pyld_unit_size is 1500, fragment offset of the second
UDP fragment will be 187 (i.e. 1500 / 8), which means 1496,
and it will result in 4-byte data loss (1500 - 1496 = 4).
So UDP GRO will reassemble out a wrong packet.

Fixes: b166d4f30b66 ("gso: support UDP/IPv4 fragmentation")

Signed-off-by: Yi Yang <yangyi01@inspur.com>
---
 lib/librte_gso/gso_udp4.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/librte_gso/gso_udp4.c b/lib/librte_gso/gso_udp4.c
index 21fea09..6fa68f2 100644
--- a/lib/librte_gso/gso_udp4.c
+++ b/lib/librte_gso/gso_udp4.c
@@ -69,7 +69,10 @@
 		return 1;
 	}
 
-	pyld_unit_size = gso_size - hdr_offset;
+	/* pyld_unit_size must be a multiple of 8 because frag_off
+	 * uses 8 bytes as unit.
+	 */
+	pyld_unit_size = (gso_size - hdr_offset) & ~7U;
 
 	/* Segment the payload */
 	ret = gso_do_segment(pkt, hdr_offset, pyld_unit_size, direct_pool,
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2020-09-17 15:02 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-09-17  2:12 [dpdk-dev] [PATCH v2] gso: fix pyld_unit_size issue for udp gso yang_y_yi
2020-09-17  2:16 ` Hu, Jiayu
2020-09-17 15:01   ` Ferruh Yigit

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