Commit 3093ee18 authored by Lv Yunlong's avatar Lv Yunlong Committed by Jason Gunthorpe
Browse files

RDMA/siw: Fix a use after free in siw_alloc_mr 

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: 2251334d ("rdma/siw: application buffer management")
Link: https://lore.kernel.org/r/20210426011647.3561-1-lyl2019@mail.ustc.edu.cn


Signed-off-by: default avatarLv Yunlong <lyl2019@mail.ustc.edu.cn>
Reviewed-by: default avatarBernard Metzler <bmt@zurich.ihm.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 2d085ee1

drivers/infiniband/sw/siw/siw_mem.c

+2 −2
Original line number Diff line number Diff line
@@ -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;