From 128394eff343fc6d2f32172f03e24829539c5835 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 16 Dec 2016 13:42:06 -0500 Subject: [PATCH] sg_write()/bsg_write() is not fit to be called under KERNEL_DS Both damn things interpret userland pointers embedded into the payload; worse, they are actually traversing those. Leaving aside the bad API design, this is very much _not_ safe to call with KERNEL_DS. Bail out early if that happens. Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- block/bsg.c | 3 +++ drivers/scsi/sg.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/block/bsg.c b/block/bsg.c index 8a05a404ae70..a57046de2f07 100644 --- a/block/bsg.c +++ b/block/bsg.c @@ -655,6 +655,9 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) dprintk("%s: write %Zd bytes\n", bd->name, count); + if (unlikely(segment_eq(get_fs(), KERNEL_DS))) + return -EINVAL; + bsg_set_block(bd, file); bytes_written = 0; diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 070332eb41f3..dbe5b4b95df0 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -581,6 +581,9 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos) sg_io_hdr_t *hp; unsigned char cmnd[SG_MAX_CDB_SIZE]; + if (unlikely(segment_eq(get_fs(), KERNEL_DS))) + return -EINVAL; + if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp))) return -ENXIO; SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp, -- 2.20.1