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authorMartin KaFai Lau <kafai@fb.com>2021-07-01 22:05:41 +0200
committerAndrii Nakryiko <andrii@kernel.org>2021-07-24 01:43:24 +0200
commit525e2f9fd0229eb10cb460a9e6d978257f24804e (patch)
treeba158dcde9d92518e42a730037b5f28eb8a6aa56 /net/decnet
parentlibbpf: Export bpf_program__attach_kprobe_opts function (diff)
downloadlinux-525e2f9fd0229eb10cb460a9e6d978257f24804e.tar.xz
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tcp: seq_file: Avoid skipping sk during tcp_seek_last_pos
st->bucket stores the current bucket number. st->offset stores the offset within this bucket that is the sk to be seq_show(). Thus, st->offset only makes sense within the same st->bucket. These two variables are an optimization for the common no-lseek case. When resuming the seq_file iteration (i.e. seq_start()), tcp_seek_last_pos() tries to continue from the st->offset at bucket st->bucket. However, it is possible that the bucket pointed by st->bucket has changed and st->offset may end up skipping the whole st->bucket without finding a sk. In this case, tcp_seek_last_pos() currently continues to satisfy the offset condition in the next (and incorrect) bucket. Instead, regardless of the offset value, the first sk of the next bucket should be returned. Thus, "bucket == st->bucket" check is added to tcp_seek_last_pos(). The chance of hitting this is small and the issue is a decade old, so targeting for the next tree. Fixes: a8b690f98baf ("tcp: Fix slowness in read /proc/net/tcp") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210701200541.1033917-1-kafai@fb.com
Diffstat (limited to 'net/decnet')
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