scsi: fix memory leak with scsi-mq (0c958ecc) · Commits · 戴 / test

Fix a memory leak with scsi-mq triggered by commands with large data transfer length. __sg_alloc_table() sets both table->nents and table->orig_nents to the same value. When the scatterlist is DMA-mapped, table->nents is overwritten with the (possibly smaller) size of the DMA-mapped scatterlist, while table->orig_nents retains the original size of the allocated scatterlist. scsi_free_sgtable() should therefore check orig_nents instead of nents, and all code that initializes sdb->table without calling __sg_alloc_table() should set both nents and orig_nents. Fixes: ("scsi: add support for a blk-mq based I/O path.") Cc: <stable@vger.kernel.org> # 3.17+ Signed-off-by:

Tony Battersby <tonyb@cybernetics.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Reviewed-by:

Ewan D. Milne <emilne@redhat.com> Signed-off-by:

James Bottomley <JBottomley@Odin.com>

drivers/scsi/scsi_error.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -944,7 +944,7 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd scmd, struct scsi_eh_save ses,
		scmd->sdb.length);
		scmd->sdb.table.sgl = &ses->sense_sgl;
		scmd->sc_data_direction = DMA_FROM_DEVICE;
		scmd->sdb.table.nents = 1;
		scmd->sdb.table.nents = scmd->sdb.table.orig_nents = 1;
		scmd->cmnd[0] = REQUEST_SENSE;
		scmd->cmnd[4] = scmd->sdb.length;
		scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);

drivers/scsi/scsi_lib.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -583,7 +583,7 @@ static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)

		static void scsi_free_sgtable(struct scsi_data_buffer *sdb, bool mq)
		{
		if (mq && sdb->table.nents <= SCSI_MAX_SG_SEGMENTS)
		if (mq && sdb->table.orig_nents <= SCSI_MAX_SG_SEGMENTS)
		return;
		__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, mq, scsi_sg_free);
		}
		@@ -597,8 +597,8 @@ static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, bool mq)

		if (mq) {
		if (nents <= SCSI_MAX_SG_SEGMENTS) {
		sdb->table.nents = nents;
		sg_init_table(sdb->table.sgl, sdb->table.nents);
		sdb->table.nents = sdb->table.orig_nents = nents;
		sg_init_table(sdb->table.sgl, nents);
		return 0;
		}
		first_chunk = sdb->table.sgl;

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