linux-kernel - Re: [PATCH] bpf: decrease usercnt if bpf_map_new_fd() fails in bpf_map_get_fd_by

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Date:   Tue, 26 Feb 2019 17:33:58 +0000
From:   Martin Lau <kafai@...com>
To:     zerons <sironhide0null@...il.com>
CC:     "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] bpf: decrease usercnt if bpf_map_new_fd() fails in
 bpf_map_get_fd_by_id()

On Tue, Feb 26, 2019 at 10:15:37PM +0800, zerons wrote:
> [ Upstream commit c91951f15978f1a0c6b65f063d30f7ea7bc6fb42 ]
> 
> In bpf/syscall.c, bpf_map_get_fd_by_id() use bpf_map_inc_not_zero() to increase
> the refcount, both map->refcnt and map->usercnt. Then, if bpf_map_new_fd() fails,
> should handle map->usercnt too.
Good catch!  Thanks for the fix.

Fixes: bd5f5f4ecb78 ("bpf: Add BPF_MAP_GET_FD_BY_ID")
Acked-by: Martin KaFai Lau <kafai@...com>