| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 57/58] sg_write()/bsg_write() is not fit to be called under KERNEL_DS | Date | Fri, 6 Jan 2017 22:44:42 +0100 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro <viro@zeniv.linux.org.uk>
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: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- block/bsg.c | 3 +++ drivers/scsi/sg.c | 3 +++ 2 files changed, 6 insertions(+)
--- a/block/bsg.c +++ b/block/bsg.c @@ -655,6 +655,9 @@ bsg_write(struct file *file, const char 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; --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -592,6 +592,9 @@ sg_write(struct file *filp, const char _ 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,
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