mana_get_rxbuf_cfg() aligns the RX buffer's DMA datasize to be multiple of 64. So a packet slightly bigger than mtu+14, say 1536, can be received and cause skb_over_panic.

Sample dmesg: [ 5325.237162] skbuff: skb_over_panic: text:ffffffffc043277a len:1536 put:1536 head:ff1100018b517000 data:ff1100018b517100 tail:0x700 end:0x6ea dev:<NULL> [ 5325.243689] ------------[ cut here ]------------ [ 5325.245748] kernel BUG at net/core/skbuff.c:192! [ 5325.247838] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 5325.258374] RIP: 0010:skb_panic+0x4f/0x60 [ 5325.302941] Call Trace: [ 5325.304389] <IRQ> [ 5325.315794] ? skb_panic+0x4f/0x60 [ 5325.317457] ? asm_exc_invalid_op+0x1f/0x30 [ 5325.319490] ? skb_panic+0x4f/0x60 [ 5325.321161] skb_put+0x4e/0x50 [ 5325.322670] mana_poll+0x6fa/0xb50 [mana] [ 5325.324578] __napi_poll+0x33/0x1e0 [ 5325.326328] net_rx_action+0x12e/0x280

As discussed internally, this alignment is not necessary. To fix this bug, remove it from the code. So oversized packets will be marked as CQE_RX_TRUNCATED by NIC, and dropped.

Cc: stable@vger.kernel.org Fixes: 2fbbd712baf1 ("net: mana: Enable RX path to handle various MTU sizes") Signed-off-by: Haiyang Zhang haiyangz@microsoft.com Reviewed-by: Dexuan Cui decui@microsoft.com

--- V2: updated the "Fixes" tag. The code change remains the same.

--- drivers/net/ethernet/microsoft/mana/mana_en.c | 2 +- include/net/mana/mana.h | 1 - 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c index 59287c6e6cee..d8af5e7e15b4 100644 --- a/drivers/net/ethernet/microsoft/mana/mana_en.c +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c @@ -601,7 +601,7 @@ static void mana_get_rxbuf_cfg(int mtu, u32 *datasize, u32 *alloc_size,

*alloc_size = mtu + MANA_RXBUF_PAD + *headroom;

- *datasize = ALIGN(mtu + ETH_HLEN, MANA_RX_DATA_ALIGN); + *datasize = mtu + ETH_HLEN; }

static int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu) diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h index 76147feb0d10..4eeedf14711b 100644 --- a/include/net/mana/mana.h +++ b/include/net/mana/mana.h @@ -39,7 +39,6 @@ enum TRI_STATE { #define COMP_ENTRY_SIZE 64

#define RX_BUFFERS_PER_QUEUE 512 -#define MANA_RX_DATA_ALIGN 64

#define MAX_SEND_BUFFERS_PER_QUEUE 256