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authorYonghong Song <yhs@fb.com>2020-08-21 22:10:54 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-08-25 07:03:07 +0300
commitb474959d5afda6e341a02c85f9595d85d39189ae (patch)
treeeb61755165d1e65bdd944d7b48239392c59e31d6 /kernel
parent99408c422d336db32bfab5cbebc10038a70cf7d2 (diff)
downloadlinux-b474959d5afda6e341a02c85f9595d85d39189ae.tar.xz
bpf: Fix a buffer out-of-bound access when filling raw_tp link_info
Commit f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link") added link query for raw_tp. One of fields in link_info is to fill a user buffer with tp_name. The Scurrent checking only declares "ulen && !ubuf" as invalid. So "!ulen && ubuf" will be valid. Later on, we do "copy_to_user(ubuf, tp_name, ulen - 1)" which may overwrite user memory incorrectly. This patch fixed the problem by disallowing "!ulen && ubuf" case as well. Fixes: f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link") Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200821191054.714731-1-yhs@fb.com
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 86299a292214..ac6c784c0576 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2634,7 +2634,7 @@ static int bpf_raw_tp_link_fill_link_info(const struct bpf_link *link,
u32 ulen = info->raw_tracepoint.tp_name_len;
size_t tp_len = strlen(tp_name);
- if (ulen && !ubuf)
+ if (!ulen ^ !ubuf)
return -EINVAL;
info->raw_tracepoint.tp_name_len = tp_len + 1;