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@xxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # 8494057ab5e4 ("IB/uverbs: Prevent integer overflow in ib_umem_get address arithmetic")
Cc: Shachar Raindel <raindel@xxxxxxxxxxxx>
Cc: Jack Morgenstein <jackm@xxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
---
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.
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