vt: don't hardcode the mem allocation upper bound
commit2717769e20
upstream. The code in vc_do_resize() bounds the memory allocation size to avoid exceeding MAX_ORDER down the kzalloc() call chain and generating a runtime warning triggerable from user space. However, not only is it unwise to use a literal value here, but MAX_ORDER may also be configurable based on CONFIG_FORCE_MAX_ZONEORDER. Let's use KMALLOC_MAX_SIZE instead. Note that prior commitbb1107f7c6
("mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value could not be relied upon. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Cc: <stable@vger.kernel.org> # v4.10+ Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1206,7 +1206,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
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if (new_cols == vc->vc_cols && new_rows == vc->vc_rows)
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return 0;
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if (new_screen_size > (4 << 20))
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if (new_screen_size > KMALLOC_MAX_SIZE)
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return -EINVAL;
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newscreen = kzalloc(new_screen_size, GFP_USER);
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if (!newscreen)
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