From: Lv Yunlong lyl2019@mail.ustc.edu.cn
[ Upstream commit 3093ee182f01689b89e9f8797b321603e5de4f63 ]
Our code analyzer reported a UAF.
In siw_alloc_mr(), it calls siw_mr_add_mem(mr,..). In the implementation of siw_mr_add_mem(), mem is assigned to mr->mem and then mem is freed via kfree(mem) if xa_alloc_cyclic() failed. Here, mr->mem still point to a freed object. After, the execution continue up to the err_out branch of siw_alloc_mr, and the freed mr->mem is used in siw_mr_drop_mem(mr).
My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {} section, to avoid the uaf.
Fixes: 2251334dcac9 ("rdma/siw: application buffer management") Link: https://lore.kernel.org/r/20210426011647.3561-1-lyl2019@mail.ustc.edu.cn Signed-off-by: Lv Yunlong lyl2019@mail.ustc.edu.cn Reviewed-by: Bernard Metzler bmt@zurich.ihm.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/sw/siw/siw_mem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c index 34a910cf0edb..61c17db70d65 100644 --- a/drivers/infiniband/sw/siw/siw_mem.c +++ b/drivers/infiniband/sw/siw/siw_mem.c @@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj, mem->perms = rights & IWARP_ACCESS_MASK; kref_init(&mem->ref);
- mr->mem = mem; - get_random_bytes(&next, 4); next &= 0x00ffffff;
@@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj, kfree(mem); return -ENOMEM; } + + mr->mem = mem; /* Set the STag index part */ mem->stag = id << 8; mr->base_mr.lkey = mr->base_mr.rkey = mem->stag;