From: Eric Biggers <ebiggers@xxxxxxxxxx> Subject: pipe: fix off-by-one error when checking buffer limits With pipe-user-pages-hard set to 'N', users were actually only allowed up to 'N - 1' buffers; and likewise for pipe-user-pages-soft. Fix this to allow up to 'N' buffers, as would be expected. Link: http://lkml.kernel.org/r/20180111052902.14409-5-ebiggers3@xxxxxxxxx Fixes: b0b91d18e2e9 ("pipe: fix limit checking in pipe_set_size()") Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Acked-by: Willy Tarreau <w@xxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Acked-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: "Luis R . Rodriguez" <mcgrof@xxxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/pipe.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN fs/pipe.c~pipe-fix-off-by-one-error-when-checking-buffer-limits fs/pipe.c --- a/fs/pipe.c~pipe-fix-off-by-one-error-when-checking-buffer-limits +++ a/fs/pipe.c @@ -605,12 +605,12 @@ static unsigned long account_pipe_buffer static bool too_many_pipe_buffers_soft(unsigned long user_bufs) { - return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft; + return pipe_user_pages_soft && user_bufs > pipe_user_pages_soft; } static bool too_many_pipe_buffers_hard(unsigned long user_bufs) { - return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard; + return pipe_user_pages_hard && user_bufs > pipe_user_pages_hard; } static bool is_unprivileged_user(void) _