/* mpi-mul.c - MPI functions * Copyright (C) 1994, 1996, 1998, 2001, 2002, * 2003 Free Software Foundation, Inc. * * This file is part of Libgcrypt. * * Note: This code is heavily based on the GNU MP Library. * Actually it's the same code with only minor changes in the * way the data is stored; this is to support the abstraction * of an optional secure memory allocation which may be used * to avoid revealing of sensitive data due to paging etc. */ #include "mpi-internal.h" void mpi_mul(MPI w, MPI u, MPI v) { mpi_size_t usize, vsize, wsize; mpi_ptr_t up, vp, wp; mpi_limb_t cy; int usign, vsign, sign_product; int assign_wp = 0; mpi_ptr_t tmp_limb = NULL; if (u->nlimbs < v->nlimbs) { /* Swap U and V. */ usize = v->nlimbs; usign = v->sign; up = v->d; vsize = u->nlimbs; vsign = u->sign; vp = u->d; } else { usize = u->nlimbs; usign = u->sign; up = u->d; vsize = v->nlimbs; vsign = v->sign; vp = v->d; } sign_product = usign ^ vsign; wp = w->d; /* Ensure W has space enough to store the result. */ wsize = usize + vsize; if (w->alloced < wsize) { if (wp == up || wp == vp) { wp = mpi_alloc_limb_space(wsize); assign_wp = 1; } else { mpi_resize(w, wsize); wp = w->d; } } else { /* Make U and V not overlap with W. */ if (wp == up) { /* W and U are identical. Allocate temporary space for U. */ up = tmp_limb = mpi_alloc_limb_space(usize); /* Is V identical too? Keep it identical with U. */ if (wp == vp) vp = up; /* Copy to the temporary space. */ MPN_COPY(up, wp, usize); } else if (wp == vp) { /* W and V are identical. Allocate temporary space for V. */ vp = tmp_limb = mpi_alloc_limb_space(vsize); /* Copy to the temporary space. */ MPN_COPY(vp, wp, vsize); } } if (!vsize) wsize = 0; else { mpihelp_mul(wp, up, usize, vp, vsize, &cy); wsize -= cy ? 0:1; } if (assign_wp) mpi_assign_limb_space(w, wp, wsize); w->nlimbs = wsize; w->sign = sign_product; if (tmp_limb) mpi_free_limb_space(tmp_limb); } void mpi_mulm(MPI w, MPI u, MPI v, MPI m) { mpi_mul(w, u, v); mpi_tdiv_r(w, w, m); } EXPORT_SYMBOL_GPL(mpi_mulm); r
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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-17 13:58:16 -0600
committerDavid S. Miller <davem@davemloft.net>2020-02-17 19:05:05 -0800
commitdc3cc347d2ce77da41f120a6162b40c6139df754 (patch)
tree7039eb6880c9d1a0c351db44efc29efd0329c567 /drivers/net
parent725d23b59cd18074f0bdc1ce94d71e3d734adab6 (diff)
net: usb: cdc-phonet: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')