kernel/linux.git/include/linux/math.h, branch v6.6.132

crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()

2025-07-17T16:35:22+00:00

commit b16510a530d1e6ab9683f04f8fb34f2e0f538275 upstream. 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 Signed-off-by: Lukas Wunner Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

drm/i915: Move abs_diff() to math.h

2023-08-18T17:18:59+00:00

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 Reviewed-by: Jiri Slaby # tty/serial Acked-by: Jani Nikula Acked-by: Greg Kroah-Hartman Reviewed-by: Andi Shyti Reviewed-by: Philipp Zabel # gpu/ipu-v3 Cc: Alexey Dobriyan Cc: Daniel Vetter Cc: David Airlie Cc: Helge Deller Cc: Imre Deak Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rasmus Villemoes Cc: Rodrigo Vivi Cc: Tvrtko Ursulin Cc: Randy Dunlap Signed-off-by: Andrew Morton

include/linux/math.h: fix mult_frac() multiple argument evaluation bug

2023-06-10T00:44:22+00:00

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 Signed-off-by: Andrew Morton

math.h: Introduce data types for fractional numbers

2022-01-30T12:21:25+00:00

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 Link: https://lore.kernel.org/r/20220126135353.24007-1-andriy.shevchenko@linux.intel.com Signed-off-by: Jonathan Cameron

kernel.h: split out mathematical helpers

2020-12-16T06:46:15+00:00

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 Cc: "Paul E. McKenney" Cc: Trond Myklebust Cc: Jeff Layton Cc: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds