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| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2011-10-24 22:35:37 +0200 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2011-10-26 22:42:13 +0200 |
| commit | 8cd79f24350826b81e16990d9e12bc878e67d385 (patch) | |
| tree | 14421b42c8c7eeb566e5793c1dfd45d051cd74d6 /drivers/target/loopback | |
| parent | target: Fix compile warning w/ missing module.h include (diff) | |
| download | linux-8cd79f24350826b81e16990d9e12bc878e67d385.tar.xz linux-8cd79f24350826b81e16990d9e12bc878e67d385.zip | |
tcm_loop: Add explict read buffer memset for SCF_SCSI_CONTROL_SG_IO_CDB
This patch addresses an issue with buggy userspace code sending I/O
via scsi-generic that does not explictly clear their associated read
buffers. It adds an explict memset of the first SGL entry within
tcm_loop_new_cmd_map() for SCF_SCSI_CONTROL_SG_IO_CDB payloads that
are currently guaranteed to be a single SGL by target-core code.
This issue is a side effect of the v3.1-rc1 merge to remove the
extra memcpy between certain control CDB types using a contigious
+ cleared buffer in target-core, and performing a memcpy into the
SGL list within tcm_loop.
It was originally mainfesting itself by udev + scsi_id + scsi-generic
not properly setting up the expected /dev/disk/by-id/ symlinks because
the INQUIRY payload was containing extra bogus data preventing the
proper NAA IEEE WWN from being parsed by userspace.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/loopback')
| -rw-r--r-- | drivers/target/loopback/tcm_loop.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c index b15d8cbf630b..3c9c318f66ed 100644 --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -174,6 +174,24 @@ static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd) sgl_bidi = sdb->table.sgl; sgl_bidi_count = sdb->table.nents; } + /* + * Because some userspace code via scsi-generic do not memset their + * associated read buffers, go ahead and do that here for type + * SCF_SCSI_CONTROL_SG_IO_CDB. Also note that this is currently + * guaranteed to be a single SGL for SCF_SCSI_CONTROL_SG_IO_CDB + * by target core in transport_generic_allocate_tasks() -> + * transport_generic_cmd_sequencer(). + */ + if (se_cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB && + se_cmd->data_direction == DMA_FROM_DEVICE) { + struct scatterlist *sg = scsi_sglist(sc); + unsigned char *buf = kmap(sg_page(sg)) + sg->offset; + + if (buf != NULL) { + memset(buf, 0, sg->length); + kunmap(sg_page(sg)); + } + } /* Tell the core about our preallocated memory */ ret = transport_generic_map_mem_to_cmd(se_cmd, scsi_sglist(sc), |