From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: [PATCH 2/2] bpf: do not use KMALLOC_SHIFT_MAX Date: Tue, 20 Dec 2016 14:06:59 +0100 Message-ID: <20161220130659.16461-3-mhocko@kernel.org> References: <20161220130659.16461-1-mhocko@kernel.org> Cc: Cristopher Lameter , Alexei Starovoitov , Andrey Konovalov , netdev@vger.kernel.org, , LKML , Michal Hocko To: Andrew Morton Return-path: In-Reply-To: <20161220130659.16461-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org From: Michal Hocko 01b3f52157ff ("bpf: fix allocation warnings in bpf maps and integer overflow") has added checks for the maximum allocateable size. It (ab)used KMALLOC_SHIFT_MAX for that purpose. While this is not incorrect it is not very clean because we already have KMALLOC_MAX_SIZE for this very reason so let's change both checks to use KMALLOC_MAX_SIZE instead. The original motivation for using KMALLOC_SHIFT_MAX was to work around an incorrect KMALLOC_MAX_SIZE which could lead to allocation warnings but it is no longer needed since "slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER". Signed-off-by: Michal Hocko Acked-by: Christoph Lameter --- kernel/bpf/arraymap.c | 2 +- kernel/bpf/hashtab.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index a2ac051c342f..229a5d5df977 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -56,7 +56,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) attr->value_size == 0 || attr->map_flags) return ERR_PTR(-EINVAL); - if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1)) + if (attr->value_size > KMALLOC_MAX_SIZE) /* if value_size is bigger, the user space won't be able to * access the elements. */ diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index ad1bc67aff1b..c5ec7dc71c84 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -181,7 +181,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) */ goto free_htab; - if (htab->map.value_size >= (1 << (KMALLOC_SHIFT_MAX - 1)) - + if (htab->map.value_size >= KMALLOC_MAX_SIZE - MAX_BPF_STACK - sizeof(struct htab_elem)) /* if value_size is bigger, the user space won't be able to * access the elements via bpf syscall. This check also makes -- 2.10.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org