Patch "IB/core: don't disallow registering region starting at 0x0" has been added to the 3.10-stable tree

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

    IB/core: don't disallow registering region starting at 0x0

to the 3.10-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:

     ib-core-don-t-disallow-registering-region-starting-at-0x0.patch

and it can be found in the queue-3.10 subdirectory.

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

From: Yann Droneaud <[email protected]>
Date: Mon, 13 Apr 2015 14:56:23 +0200
Subject: IB/core: don't disallow registering region starting at 0x0

From: Yann Droneaud <[email protected]>

commit 66578b0b2f69659f00b6169e6fe7377c4b100d18 upstream.

In a call to ib_umem_get(), if address is 0x0 and size is already page aligned, check added in commit 8494057ab5e4 ("IB/uverbs: Prevent integer overflow in ib_umem_get address arithmetic") will refuse to register a memory region that could otherwise be valid (provided vm.mmap_min_addr sysctl and mmap_low_allowed SELinux knobs allow userspace to map something at address 0x0).

This patch allows back such registration: ib_umem_get() should probably don't care of the base address provided it can be pinned with get_user_pages().

There's two possible overflows, in (addr + size) and in PAGE_ALIGN(addr + size), this patch keep ensuring none of them happen while allowing to pin memory at address 0x0. Anyway, the case of size equal 0 is no more (partially) handled as 0-length memory region are disallowed by an earlier check.

---
 drivers/infiniband/core/umem.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -101,8 +101,8 @@ struct ib_umem *ib_umem_get(struct ib_uc
 	 * If the combination of the addr and size requested for this memory
 	 * region causes an integer overflow, return error.
 	 */
-	if ((PAGE_ALIGN(addr + size) <= size) ||
-	    (PAGE_ALIGN(addr + size) <= addr))
+	if (((addr + size) < addr) ||
+	    PAGE_ALIGN(addr + size) < (addr + size))
 		return ERR_PTR(-EINVAL);
 
 	if (!can_do_mlock())

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

queue-3.10/ib-core-don-t-disallow-registering-region-starting-at-0x0.patch queue-3.10/ib-core-disallow-registering-0-sized-memory-region.patch