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RDMA/siw: Fix a use after free in siw_alloc_mr

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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: 2251334dca ("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>
This commit is contained in:
Lv Yunlong 2021-04-25 18:16:47 -07:00 committed by Jason Gunthorpe
parent 2d085ee172
commit 3093ee182f
1 changed files with 2 additions and 2 deletions
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4
drivers/infiniband/sw/siw/siw_mem.c
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@ -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;