| Message ID | 20181025143131.4048-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | RDMA/cxgb3: Fix unintended sign extension | expand |
On 10/25/2018 9:31 AM, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > In the expression "utx_len << 28", utx_len starts as u8, but is promoted > to a signed int, then sign-extended to u64. If utx_len is 0xf8 or greater > then the sign extension will set all the upper bits of utx_cmd which is > probably not what was intended. Cast to utx_len to u64 to avoid the sign > extension. > > Detected by CoverityScan, CID#138764 ("Unintended sign extension") > > Fixes: b038ced7b370 ("RDMA/cxgb3: Add driver for Chelsio T3 RNIC") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > drivers/infiniband/hw/cxgb3/cxio_hal.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/infiniband/hw/cxgb3/cxio_hal.c b/drivers/infiniband/hw/cxgb3/cxio_hal.c > index dcb4bba522ba..c5cb80ccc6d6 100644 > --- a/drivers/infiniband/hw/cxgb3/cxio_hal.c > +++ b/drivers/infiniband/hw/cxgb3/cxio_hal.c > @@ -647,7 +647,7 @@ static int cxio_hal_ctrl_qp_write_mem(struct cxio_rdev *rdev_p, u32 addr, > wqe += (sizeof(struct t3_bypass_wr) >> 3); > utx_cmd = (T3_UTX_MEM_WRITE << 28) | (addr + i * 3); > utx_cmd <<= 32; > - utx_cmd |= (utx_len << 28) | ((utx_len << 2) + 1); > + utx_cmd |= ((u64)utx_len << 28) | ((utx_len << 2) + 1); > *wqe = cpu_to_be64(utx_cmd); > wqe++; > copy_data = (u8 *) data + i * 96; > Acked-by: Steve Wise <swise@chelsio.com>
From: Colin King > Sent: 25 October 2018 15:32 > > From: Colin Ian King <colin.king@canonical.com> > > In the expression "utx_len << 28", utx_len starts as u8, but is promoted > to a signed int, then sign-extended to u64. If utx_len is 0xf8 or greater > then the sign extension will set all the upper bits of utx_cmd which is > probably not what was intended. Cast to utx_len to u64 to avoid the sign > extension. RTFC... utx_len is only ever 1, 2 or 3. The 'problem' would arise if utx_len << 28 set the high bit. This can only happen if utx_len is more than 7 (NFI where 0xf8 came from). In any case the best fix is to use 'unsigned int' for wr_len and utx_len. There is no point making local variable (or functions parameters/results) smaller that 'int' unless you explicitly want the arithmetic to wrap. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/drivers/infiniband/hw/cxgb3/cxio_hal.c b/drivers/infiniband/hw/cxgb3/cxio_hal.c index dcb4bba522ba..c5cb80ccc6d6 100644 --- a/drivers/infiniband/hw/cxgb3/cxio_hal.c +++ b/drivers/infiniband/hw/cxgb3/cxio_hal.c @@ -647,7 +647,7 @@ static int cxio_hal_ctrl_qp_write_mem(struct cxio_rdev *rdev_p, u32 addr, wqe += (sizeof(struct t3_bypass_wr) >> 3); utx_cmd = (T3_UTX_MEM_WRITE << 28) | (addr + i * 3); utx_cmd <<= 32; - utx_cmd |= (utx_len << 28) | ((utx_len << 2) + 1); + utx_cmd |= ((u64)utx_len << 28) | ((utx_len << 2) + 1); *wqe = cpu_to_be64(utx_cmd); wqe++; copy_data = (u8 *) data + i * 96;