From: Wu Bo <wubo40@xxxxxxxxxx> [ Upstream commit 83c6f2390040f188cc25b270b4befeb5628c1aee ] If the __copy_from_user function failed we need to call sg_remove_request in sg_write. Link: https://lore.kernel.org/r/610618d9-e983-fd56-ed0f-639428343af7@xxxxxxxxxx Acked-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Signed-off-by: Wu Bo <wubo40@xxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> [groeck: Backport to v5.4.y and older kernels] Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- This patch fixes CVE-2020-12770, and the problem it fixes looks like a valid bug. Please apply to v5.4.y and older kernel branches. drivers/scsi/sg.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 94af30f768f7..9c6bf13daaee 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -689,8 +689,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos) hp->flags = input_size; /* structure abuse ... */ hp->pack_id = old_hdr.pack_id; hp->usr_ptr = NULL; - if (__copy_from_user(cmnd, buf, cmd_size)) + if (__copy_from_user(cmnd, buf, cmd_size)) { + sg_remove_request(sfp, srp); return -EFAULT; + } /* * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV, * but is is possible that the app intended SG_DXFER_TO_DEV, because there -- 2.17.1
