Commit 9393c8de628cf0968d81a17cc11841e42191e041
Committed by
Martin K. Petersen
1 parent
8b1062d513
scsi: core: Handle drivers which set sg_tablesize to zero
In scsi_mq_setup_tags(), cmd_size is calculated based on zero size for the scatter-gather list in case the low level driver uses SG_NONE in its host template. cmd_size is passed on to the block layer for calculation of the request size, and we've seen NULL pointer dereference errors from the block layer in drivers where SG_NONE is used and a mq IO scheduler is active, apparently as a consequence of this (see commit 68ab2d76e4be ("scsi: cxlflash: Set sg_tablesize to 1 instead of SG_NONE"), and a recent patch by Finn Thain converting the three m68k NFR5380 drivers to avoid setting SG_NONE). Try to avoid these errors by accounting for at least one sg list entry when calculating cmd_size, regardless of whether the low level driver set a zero sg_tablesize. Tested on 030 m68k with the atari_scsi driver - setting sg_tablesize to SG_NONE no longer results in a crash when loading this driver. CC: Finn Thain <fthain@telegraphics.com.au> Link: https://lore.kernel.org/r/1572922150-4358-1-git-send-email-schmitzmic@gmail.com Signed-off-by: Michael Schmitz <schmitzmic@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Showing 1 changed file with 2 additions and 1 deletions Side-by-side Diff
drivers/scsi/scsi_lib.c
... | ... | @@ -1882,7 +1882,8 @@ |
1882 | 1882 | { |
1883 | 1883 | unsigned int cmd_size, sgl_size; |
1884 | 1884 | |
1885 | - sgl_size = scsi_mq_inline_sgl_size(shost); | |
1885 | + sgl_size = max_t(unsigned int, sizeof(struct scatterlist), | |
1886 | + scsi_mq_inline_sgl_size(shost)); | |
1886 | 1887 | cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size; |
1887 | 1888 | if (scsi_host_get_prot(shost)) |
1888 | 1889 | cmd_size += sizeof(struct scsi_data_buffer) + |