Patch "staging/lustre/lov: remove set_fs() call from lov_getstripe()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

staging/lustre/lov: remove set_fs() call from lov_getstripe()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-lustre-lov-remove-set_fs-call-from-lov_getstripe.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Oleg Drokin <[email protected]>
Date: Fri, 26 May 2017 23:40:33 -0400
Subject: staging/lustre/lov: remove set_fs() call from lov_getstripe()

From: Oleg Drokin <[email protected]>

commit 0a33252e060e97ed3fbdcec9517672f1e91aaef3 upstream.

lov_getstripe() calls set_fs(KERNEL_DS) so that it can handle a struct lov_user_md pointer from user- or kernel-space. This changes the behavior of copy_from_user() on SPARC and may result in a misaligned access exception which in turn oopses the kernel. In fact the relevant argument to lov_getstripe() is never called with a kernel-space pointer and so changing the address limits is unnecessary and so we remove the calls to save, set, and restore the address limits.

Reviewed-on: http://review.whamcloud.com/6150
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3221

---
 drivers/staging/lustre/lustre/lov/lov_pack.c |    9 ---------
 1 file changed, 9 deletions(-)

@@ -387,18 +387,10 @@ int lov_getstripe(struct lov_object *obj
 	struct lov_mds_md *lmmk = NULL;
 	int rc, lmmk_size, lmm_size;
 	int lum_size;
-	mm_segment_t seg;
 
 	if (!lsm)
 		return -ENODATA;
 
-	/*
-	 * "Switch to kernel segment" to allow copying from kernel space by
-	 * copy_{to,from}_user().
-	 */
-	seg = get_fs();
-	set_fs(KERNEL_DS);
-
 	/* we only need the header part from user space to get lmm_magic and
 	 * lmm_stripe_count, (the header part is common to v1 and v3)
 	 */

@@ -478,6 +470,5 @@ int lov_getstripe(struct lov_object *obj
 out_free:
 	kfree(lmmk);
 out:
-	set_fs(seg);
 	return rc;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/staging-lustre-lov-remove-set_fs-call-from-lov_getstripe.patch