[PATCH][next] octeontx2-pf: Fix unintentional sign extension issue

[PATCH][next] octeontx2-pf: Fix unintentional sign extension issue

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The shifting of the u16 result from ntohs(proto) by 16 bits to the
left will be promoted to a 32 bit signed int and then sign-extended
to a u64.  In the event that the top bit of the return from ntohs(proto)
is set then all then all the upper 32 bits of a 64 bit long end up as
also being set because of the sign-extension. Fix this by casting to
a u64 long before the shift.

Addresses-Coverity: ("Unintended sign extension")
Fixes: f0c2982aaf98 ("octeontx2-pf: Add support for SR-IOV management function")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
index 4c82f60f3cf3..634d60655a74 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
@@ -2084,7 +2084,7 @@ static int otx2_do_set_vf_vlan(struct otx2_nic *pf, int vf, u16 vlan, u8 qos,
 	vtag_req->vtag_size = VTAGSIZE_T4;
 	vtag_req->cfg_type = 0; /* tx vlan cfg */
 	vtag_req->tx.cfg_vtag0 = 1;
-	vtag_req->tx.vtag0 = (ntohs(proto) << 16) | vlan;
+	vtag_req->tx.vtag0 = ((u64)ntohs(proto) << 16) | vlan;
 
 	err = otx2_sync_mbox_msg(&pf->mbox);
 	if (err)
-- 
2.28.0

Re: [PATCH][next] octeontx2-pf: Fix unintentional sign extension issue

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Wed, 18 Nov 2020 13:05:20 +0000 you wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The shifting of the u16 result from ntohs(proto) by 16 bits to the
> left will be promoted to a 32 bit signed int and then sign-extended
> to a u64.  In the event that the top bit of the return from ntohs(proto)
> is set then all then all the upper 32 bits of a 64 bit long end up as
> also being set because of the sign-extension. Fix this by casting to
> a u64 long before the shift.
> 
> [...]

Here is the summary with links:
  - [next] octeontx2-pf: Fix unintentional sign extension issue
    https://git.kernel.org/netdev/net-next/c/583b273dea75

You are awesome, thank you!
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