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SubjectRe: [PATCH for-next v2] RDMA/rxe: Fix mr->map double free
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在 2022/10/30 11:04, Li Zhijian 写道:
> rxe_mr_cleanup() which tries to free mr->map again will be called
> when rxe_mr_init_user() fails.
>
> [43895.939883] CPU: 0 PID: 4917 Comm: rdma_flush_serv Kdump: loaded Not tainted 6.1.0-rc1-roce-flush+ #25
> [43895.942341] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> [43895.945208] Call Trace:
> [43895.946130] <TASK>
> [43895.946931] dump_stack_lvl+0x45/0x5d
> [43895.948049] panic+0x19e/0x349
> [43895.949010] ? panic_print_sys_info.part.0+0x77/0x77
> [43895.950356] ? asm_sysvec_apic_timer_interrupt+0x16/0x20
> [43895.952589] ? preempt_count_sub+0x14/0xc0
> [43895.953809] end_report.part.0+0x54/0x7c
> [43895.954993] ? rxe_mr_cleanup+0x9d/0xf0 [rdma_rxe]
> [43895.956406] kasan_report.cold+0xa/0xf
> [43895.957668] ? rxe_mr_cleanup+0x9d/0xf0 [rdma_rxe]
> [43895.959090] rxe_mr_cleanup+0x9d/0xf0 [rdma_rxe]
> [43895.960502] __rxe_cleanup+0x10a/0x1e0 [rdma_rxe]
> [43895.961983] rxe_reg_user_mr+0xb7/0xd0 [rdma_rxe]
> [43895.963456] ib_uverbs_reg_mr+0x26a/0x480 [ib_uverbs]
> [43895.964921] ? __lock_acquire+0x876/0x31e0
> [43895.966182] ? ib_uverbs_ex_create_wq+0x630/0x630 [ib_uverbs]
> [43895.967739] ? uverbs_fill_udata+0x1c6/0x330 [ib_uverbs]
> [43895.969204] ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0x1a2/0x250 [ib_uverbs]
> [43895.971126] ? ib_uverbs_handler_UVERBS_METHOD_QUERY_CONTEXT+0x1a0/0x1a0 [ib_uverbs]
> [43895.973094] ? ib_uverbs_handler_UVERBS_METHOD_QUERY_CONTEXT+0x1a0/0x1a0 [ib_uverbs]
> [43895.975096] ? uverbs_fill_udata+0x25f/0x330 [ib_uverbs]
> [43895.976466] ib_uverbs_cmd_verbs+0x1397/0x15a0 [ib_uverbs]
> [43895.977930] ? ib_uverbs_handler_UVERBS_METHOD_QUERY_CONTEXT+0x1a0/0x1a0 [ib_uverbs]
> [43895.979937] ? uverbs_fill_udata+0x330/0x330 [ib_uverbs]
>
> This issue was fistrly exposed since
> commit: b18c7da63fcb ("RDMA/rxe: Fix memory leak in error path code")
> and then we fixed it in
> commit: 8ff5f5d9d8cf ("RDMA/rxe: Prevent double freeing rxe_map_set()")
> but this fix was reverted together at last by
> commit: 1e75550648da (Revert "RDMA/rxe: Create duplicate mapping tables for FMRs")
>
> Fixes: 1e75550648da (Revert "RDMA/rxe: Create duplicate mapping tables for FMRs")
> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
> ---
> drivers/infiniband/sw/rxe/rxe_mr.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> index d4f10c2d1aa7..7c99d1591580 100644
> --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> @@ -99,6 +99,7 @@ static int rxe_mr_alloc(struct rxe_mr *mr, int num_buf)
> kfree(mr->map[i]);
>
> kfree(mr->map);
> + mr->map = NULL;
> err1:
> return -ENOMEM;
> }
> @@ -122,7 +123,6 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
> int num_buf;
> void *vaddr;
> int err;
> - int i;
>
> umem = ib_umem_get(&rxe->ib_dev, start, length, access);
> if (IS_ERR(umem)) {
> @@ -163,9 +163,8 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
> pr_warn("%s: Unable to get virtual address\n",
> __func__);
> err = -ENOMEM;
> - goto err_cleanup_map;
> + goto err_release_umem;

This call trace results from page_address's returning NULL, then goto
err_cleanup_map where mr->map[i] and mr->map are freed.

And finally rxe_reg_user_mr gets an error from rxe_mr_init_user, the
function rxe_mr_cleanup is called to handle mr to free mr->map[i] and
mr->map again.

So mr->map[i] and mr->map are double freed.

As such, this commit is reasonable.

But why page_address will return NULL?

Zhu Yanjun

> }
> -
> buf->addr = (uintptr_t)vaddr;
> buf->size = PAGE_SIZE;
> num_buf++;
> @@ -182,10 +181,6 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
>
> return 0;
>
> -err_cleanup_map:
> - for (i = 0; i < mr->num_map; i++)
> - kfree(mr->map[i]);
> - kfree(mr->map);
> err_release_umem:
> ib_umem_release(umem);
> err_out:

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