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iwlwifi: pcie: fix access to scratch buffer

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commit d5d0689aefc59c6a5352ca25d7e6d47d03f543ce upstream.

This fixes a pretty ancient bug that hasn't manifested itself
until now.
The scratchbuf for command queue is allocated only for 32 slots
but is accessed with the queue write pointer - which can be
up to 256.
Since the scratch buf size was 16 and there are up to 256 TFDs
we never passed a page boundary when accessing the scratch buffer,
but when attempting to increase the size of the scratch buffer a
panic was quick to follow when trying to access the address resulted
in a page boundary.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Fixes: 38c0f334b359 ("iwlwifi: use coherent DMA memory for command header")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sara Sharon 2016-06-09 17:19:35 +03:00 committed by Greg Kroah-Hartman
parent 0d5b1752c8
commit 40dc71547d
1 changed files with 2 additions and 2 deletions
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4
drivers/net/wireless/iwlwifi/pcie/tx.c
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@ -1508,9 +1508,9 @@ static int iwl_pcie_enqueue_hcmd(struct iwl_trans *trans,
/* start the TFD with the scratchbuf */
scratch_size = min_t(int, copy_size, IWL_HCMD_SCRATCHBUF_SIZE);
memcpy(&txq->scratchbufs[q->write_ptr], &out_cmd->hdr, scratch_size);
memcpy(&txq->scratchbufs[idx], &out_cmd->hdr, scratch_size);
iwl_pcie_txq_build_tfd(trans, txq,
iwl_pcie_get_scratchbuf_dma(txq, q->write_ptr),
iwl_pcie_get_scratchbuf_dma(txq, idx),
scratch_size, true);
/* map first command fragment, if any remains */