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2025-02-09crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()Lukas Wunner
Herbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa implementation's ->key_size() callback returns an unusually large value. Herbert instead suggests (for a division by 8): X / 8 + !!(X & 7) Based on this formula, introduce a generic DIV_ROUND_UP_POW2() macro and use it in lieu of DIV_ROUND_UP() for ->key_size() return values. Additionally, use the macro in ecc_digits_from_bytes(), whose "nbytes" parameter is a ->key_size() return value in some instances, or a user-specified ASN.1 length in the case of ecdsa_get_signature_rs(). Link: https://lore.kernel.org/r/Z3iElsILmoSu6FuC@gondor.apana.org.au/ Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2024-07-01math.h: Add unsigned 8 bits fractional numbers typeAngeloGioacchino Del Regno
Some users may be requiring only rather small numbers as both numerator and denominator: add signed and unsigned 8 bits structs {s8,u8}_fract. Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: Andy Shevchenko <andy@kernel.org> Link: https://patch.msgid.link/20240604123008.327424-4-angelogioacchino.delregno@collabora.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2023-08-18drm/i915: Move abs_diff() to math.hAndy Shevchenko
abs_diff() belongs to math.h. Move it there. This will allow others to use it. [andriy.shevchenko@linux.intel.com: add abs_diff() documentation] Link: https://lkml.kernel.org/r/20230804050934.83223-1-andriy.shevchenko@linux.intel.com [akpm@linux-foundation.org: fix comment, per Randy] Link: https://lkml.kernel.org/r/20230803131918.53727-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> # tty/serial Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> # gpu/ipu-v3 Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Imre Deak <imre.deak@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09include/linux/math.h: fix mult_frac() multiple argument evaluation bugAlexey Dobriyan
mult_frac() evaluates _all_ arguments multiple times in the body. Clarify comment while I'm at it. Link: https://lkml.kernel.org/r/f9f9fdbb-ec8e-4f5e-a998-2a58627a1a43@p183 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-01-30math.h: Introduce data types for fractional numbersAndy Shevchenko
Introduce a macro to produce data types like struct TYPE_fract { __TYPE numerator; __TYPE denominator; }; to be used in the code wherever it's needed. In the following changes convert some users to it. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20220126135353.24007-1-andriy.shevchenko@linux.intel.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2020-12-15kernel.h: split out mathematical helpersAndy Shevchenko
kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out mathematical helpers. At the same time convert users in header and lib folder to use new header. Though for time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [sfr@canb.auug.org.au: fix powerpc build] Link: https://lkml.kernel.org/r/20201029150809.13059608@canb.auug.org.au Link: https://lkml.kernel.org/r/20201028173212.41768-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>