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pipe: fix off-by-one error when checking buffer limits 

commit 9903a91c76 upstream.

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@gmail.com
Fixes: b0b91d18e2 ("pipe: fix limit checking in pipe_set_size()")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Eric Biggers 2018-02-06 15:41:56 -08:00 committed by Greg Kroah-Hartman
parent a125e9a423
commit 703b37d845
1 changed files with 2 additions and 2 deletions
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4
fs/pipe.c
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@ -610,12 +610,12 @@ static unsigned long account_pipe_buffers(struct user_struct *user,
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)