From 3e6c3b0fd5d071ed17bf91586aae35a6cfb8cdb3 Mon Sep 17 00:00:00 2001 From: Sebastian Sanchez Date: Wed, 31 Aug 2016 07:24:20 -0700 Subject: [PATCH] IB/hfi1: Fix SGE length for misaligned PIO copy When trying to align the source pointer and there's a byte carry in an SGE copy, bytes are borrowed from the next quad-word X to complete the required quad-word copy. Then, the SGE length is reduced by the number of borrowed bytes. After this, if the remaining number of bytes from quad-word X (extra bytes) is greater than the new SGE length, the number of extra bytes needs to be updated to the new SGE length. Otherwise, when the SGE length gets updated again after the extra bytes are read to create the new byte carry, it goes negative, which then becomes a very large number as the SGE length is an unsigned integer. This causes SGE buffer to be over-read. Reviewed-by: Dean Luick Signed-off-by: Sebastian Sanchez Signed-off-by: Dennis Dalessandro Signed-off-by: Doug Ledford --- drivers/infiniband/hw/hfi1/pio_copy.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/infiniband/hw/hfi1/pio_copy.c b/drivers/infiniband/hw/hfi1/pio_copy.c index 8c25e1b58849..3a1ef3056282 100644 --- a/drivers/infiniband/hw/hfi1/pio_copy.c +++ b/drivers/infiniband/hw/hfi1/pio_copy.c @@ -771,6 +771,9 @@ void seg_pio_copy_mid(struct pio_buf *pbuf, const void *from, size_t nbytes) read_extra_bytes(pbuf, from, to_fill); from += to_fill; nbytes -= to_fill; + /* may not be enough valid bytes left to align */ + if (extra > nbytes) + extra = nbytes; /* ...now write carry */ dest = pbuf->start + (pbuf->qw_written * sizeof(u64)); @@ -798,6 +801,15 @@ void seg_pio_copy_mid(struct pio_buf *pbuf, const void *from, size_t nbytes) read_low_bytes(pbuf, from, extra); from += extra; nbytes -= extra; + /* + * If no bytes are left, return early - we are done. + * NOTE: This short-circuit is *required* because + * "extra" may have been reduced in size and "from" + * is not aligned, as required when leaving this + * if block. + */ + if (nbytes == 0) + return; } /* at this point, from is QW aligned */ -- 2.11.0