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Commit d8572736 authored by Al Viro's avatar Al Viro Committed by Greg Kroah-Hartman
Browse files

sg_write()/bsg_write() is not fit to be called under KERNEL_DS 



commit 128394eff343fc6d2f32172f03e24829539c5835 upstream.

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.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7fb5a936

block/bsg.c

+3 −0
Original line number Diff line number Diff line
@@ -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;

drivers/scsi/sg.c

+3 −0
Original line number Diff line number Diff line
@@ -592,6 +592,9 @@ 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,