[PATCH 4.19 49/98] libata: add SG safety checks in SFF pio transfers

Greg Kroah-Hartman
2019-08-27T07:56:53Z

[ Upstream commit 752ead44491e8c91e14d7079625c5916b30921c5 ]

Abort processing of a command if we run out of mapped data in the
SG list. This should never happen, but a previous bug caused it to
be possible. Play it safe and attempt to abort nicely if we don't
have more SG segments left.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/ata/libata-sff.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index c5ea0fc635e54..873cc09060551 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -674,6 +674,10 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
unsigned int offset;
unsigned char *buf;

+ if (!qc->cursg) {
+ qc->curbytes = qc->nbytes;
+ return;
+ }
if (qc->curbytes == qc->nbytes - qc->sect_size)
ap->hsm_task_state = HSM_ST_LAST;

@@ -699,6 +703,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)

if (qc->cursg_ofs == qc->cursg->length) {
qc->cursg = sg_next(qc->cursg);
+ if (!qc->cursg)
+ ap->hsm_task_state = HSM_ST_LAST;
qc->cursg_ofs = 0;
}
}
--
2.20.1