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Commit 9903a91c authored by Eric Biggers's avatar Eric Biggers Committed by Linus Torvalds
Browse files

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@gmail.com


Fixes: b0b91d18 ("pipe: fix limit checking in pipe_set_size()")
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Acked-by: default avatarWilly Tarreau <w@1wt.eu>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarJoe 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>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 85c2dd54

fs/pipe.c

+2 −2
Original line number Diff line number Diff line
@@ -605,12 +605,12 @@ 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)