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

[ Upstream commit 128394eff343fc6d2f32172f03e24829539c5835 ]

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 <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/block/bsg.c b/block/bsg.c
index 276e869e686cbbdb39112f19b163e353f0ddc3ef..fc607692cfe4222b4a009205bb51ab463f1415c0 100644 (file)
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -677,6 +677,9 @@ 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 bc09f1d196c9ecd0ba4c9d8a78993e46a423e0c6..0becdb6e1ba08e933ed3c401874ef786f92e02bb 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -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,