From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH v1 2/2] IB/core: don't disallow registering region starting at 0x0 Date: Tue, 14 Apr 2015 12:20:22 +0300 Message-ID: <552CDBD6.1020205@dev.mellanox.co.il> References: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: stable-owner@vger.kernel.org To: Yann Droneaud , Roland Dreier Cc: linux-rdma@vger.kernel.org, Shachar Raindel , Jack Morgenstein , Or Gerlitz , stable@vger.kernel.org List-Id: linux-rdma@vger.kernel.org On 4/13/2015 3:56 PM, Yann Droneaud wrote: > 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. > > Link: http://mid.gmane.org/cover.1428929103.git.ydroneaud@opteya.com > Cc: # 8494057ab5e4 ("IB/uverbs: Prevent integer overflow in ib_umem_get address arithmetic") > Cc: Shachar Raindel > Cc: Jack Morgenstein > Cc: Or Gerlitz > Signed-off-by: Yann Droneaud > --- > drivers/infiniband/core/umem.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c > index 9ac4068d2088..38acb3cfc545 100644 > --- a/drivers/infiniband/core/umem.c > +++ b/drivers/infiniband/core/umem.c > @@ -106,8 +106,8 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, > * 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)) If you do change the first statement to be: (addr + size) <= addr wouldn't it cover patch #1? Sagi.