From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- lib/crypto/mpi/mpi-pow.c | 311 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 311 insertions(+) create mode 100644 lib/crypto/mpi/mpi-pow.c (limited to 'lib/crypto/mpi/mpi-pow.c') diff --git a/lib/crypto/mpi/mpi-pow.c b/lib/crypto/mpi/mpi-pow.c new file mode 100644 index 000000000..9e695a3bd --- /dev/null +++ b/lib/crypto/mpi/mpi-pow.c @@ -0,0 +1,311 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* mpi-pow.c - MPI functions + * Copyright (C) 1994, 1996, 1998, 2000 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * 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. + * The GNU MP Library itself is published under the LGPL; + * however I decided to publish this code under the plain GPL. + */ + +#include +#include +#include + +#include "mpi-internal.h" +#include "longlong.h" + +/**************** + * RES = BASE ^ EXP mod MOD + */ +int mpi_powm(MPI res, MPI base, MPI exp, MPI mod) +{ + mpi_ptr_t mp_marker = NULL, bp_marker = NULL, ep_marker = NULL; + struct karatsuba_ctx karactx = {}; + mpi_ptr_t xp_marker = NULL; + mpi_ptr_t tspace = NULL; + mpi_ptr_t rp, ep, mp, bp; + mpi_size_t esize, msize, bsize, rsize; + int msign, bsign, rsign; + mpi_size_t size; + int mod_shift_cnt; + int negative_result; + int assign_rp = 0; + mpi_size_t tsize = 0; /* to avoid compiler warning */ + /* fixme: we should check that the warning is void */ + int rc = -ENOMEM; + + esize = exp->nlimbs; + msize = mod->nlimbs; + size = 2 * msize; + msign = mod->sign; + + rp = res->d; + ep = exp->d; + + if (!msize) + return -EINVAL; + + if (!esize) { + /* Exponent is zero, result is 1 mod MOD, i.e., 1 or 0 + * depending on if MOD equals 1. */ + res->nlimbs = (msize == 1 && mod->d[0] == 1) ? 0 : 1; + if (res->nlimbs) { + if (mpi_resize(res, 1) < 0) + goto enomem; + rp = res->d; + rp[0] = 1; + } + res->sign = 0; + goto leave; + } + + /* Normalize MOD (i.e. make its most significant bit set) as required by + * mpn_divrem. This will make the intermediate values in the calculation + * slightly larger, but the correct result is obtained after a final + * reduction using the original MOD value. */ + mp = mp_marker = mpi_alloc_limb_space(msize); + if (!mp) + goto enomem; + mod_shift_cnt = count_leading_zeros(mod->d[msize - 1]); + if (mod_shift_cnt) + mpihelp_lshift(mp, mod->d, msize, mod_shift_cnt); + else + MPN_COPY(mp, mod->d, msize); + + bsize = base->nlimbs; + bsign = base->sign; + if (bsize > msize) { /* The base is larger than the module. Reduce it. */ + /* Allocate (BSIZE + 1) with space for remainder and quotient. + * (The quotient is (bsize - msize + 1) limbs.) */ + bp = bp_marker = mpi_alloc_limb_space(bsize + 1); + if (!bp) + goto enomem; + MPN_COPY(bp, base->d, bsize); + /* We don't care about the quotient, store it above the remainder, + * at BP + MSIZE. */ + mpihelp_divrem(bp + msize, 0, bp, bsize, mp, msize); + bsize = msize; + /* Canonicalize the base, since we are going to multiply with it + * quite a few times. */ + MPN_NORMALIZE(bp, bsize); + } else + bp = base->d; + + if (!bsize) { + res->nlimbs = 0; + res->sign = 0; + goto leave; + } + + if (res->alloced < size) { + /* We have to allocate more space for RES. If any of the input + * parameters are identical to RES, defer deallocation of the old + * space. */ + if (rp == ep || rp == mp || rp == bp) { + rp = mpi_alloc_limb_space(size); + if (!rp) + goto enomem; + assign_rp = 1; + } else { + if (mpi_resize(res, size) < 0) + goto enomem; + rp = res->d; + } + } else { /* Make BASE, EXP and MOD not overlap with RES. */ + if (rp == bp) { + /* RES and BASE are identical. Allocate temp. space for BASE. */ + BUG_ON(bp_marker); + bp = bp_marker = mpi_alloc_limb_space(bsize); + if (!bp) + goto enomem; + MPN_COPY(bp, rp, bsize); + } + if (rp == ep) { + /* RES and EXP are identical. Allocate temp. space for EXP. */ + ep = ep_marker = mpi_alloc_limb_space(esize); + if (!ep) + goto enomem; + MPN_COPY(ep, rp, esize); + } + if (rp == mp) { + /* RES and MOD are identical. Allocate temporary space for MOD. */ + BUG_ON(mp_marker); + mp = mp_marker = mpi_alloc_limb_space(msize); + if (!mp) + goto enomem; + MPN_COPY(mp, rp, msize); + } + } + + MPN_COPY(rp, bp, bsize); + rsize = bsize; + rsign = bsign; + + { + mpi_size_t i; + mpi_ptr_t xp; + int c; + mpi_limb_t e; + mpi_limb_t carry_limb; + + xp = xp_marker = mpi_alloc_limb_space(2 * (msize + 1)); + if (!xp) + goto enomem; + + negative_result = (ep[0] & 1) && base->sign; + + i = esize - 1; + e = ep[i]; + c = count_leading_zeros(e); + e = (e << c) << 1; /* shift the exp bits to the left, lose msb */ + c = BITS_PER_MPI_LIMB - 1 - c; + + /* Main loop. + * + * Make the result be pointed to alternately by XP and RP. This + * helps us avoid block copying, which would otherwise be necessary + * with the overlap restrictions of mpihelp_divmod. With 50% probability + * the result after this loop will be in the area originally pointed + * by RP (==RES->d), and with 50% probability in the area originally + * pointed to by XP. + */ + + for (;;) { + while (c) { + mpi_size_t xsize; + + /*if (mpihelp_mul_n(xp, rp, rp, rsize) < 0) goto enomem */ + if (rsize < KARATSUBA_THRESHOLD) + mpih_sqr_n_basecase(xp, rp, rsize); + else { + if (!tspace) { + tsize = 2 * rsize; + tspace = + mpi_alloc_limb_space(tsize); + if (!tspace) + goto enomem; + } else if (tsize < (2 * rsize)) { + mpi_free_limb_space(tspace); + tsize = 2 * rsize; + tspace = + mpi_alloc_limb_space(tsize); + if (!tspace) + goto enomem; + } + mpih_sqr_n(xp, rp, rsize, tspace); + } + + xsize = 2 * rsize; + if (xsize > msize) { + mpihelp_divrem(xp + msize, 0, xp, xsize, + mp, msize); + xsize = msize; + } + + swap(rp, xp); + rsize = xsize; + + if ((mpi_limb_signed_t) e < 0) { + /*mpihelp_mul( xp, rp, rsize, bp, bsize ); */ + if (bsize < KARATSUBA_THRESHOLD) { + mpi_limb_t tmp; + if (mpihelp_mul + (xp, rp, rsize, bp, bsize, + &tmp) < 0) + goto enomem; + } else { + if (mpihelp_mul_karatsuba_case + (xp, rp, rsize, bp, bsize, + &karactx) < 0) + goto enomem; + } + + xsize = rsize + bsize; + if (xsize > msize) { + mpihelp_divrem(xp + msize, 0, + xp, xsize, mp, + msize); + xsize = msize; + } + + swap(rp, xp); + rsize = xsize; + } + e <<= 1; + c--; + cond_resched(); + } + + i--; + if (i < 0) + break; + e = ep[i]; + c = BITS_PER_MPI_LIMB; + } + + /* We shifted MOD, the modulo reduction argument, left MOD_SHIFT_CNT + * steps. Adjust the result by reducing it with the original MOD. + * + * Also make sure the result is put in RES->d (where it already + * might be, see above). + */ + if (mod_shift_cnt) { + carry_limb = + mpihelp_lshift(res->d, rp, rsize, mod_shift_cnt); + rp = res->d; + if (carry_limb) { + rp[rsize] = carry_limb; + rsize++; + } + } else { + MPN_COPY(res->d, rp, rsize); + rp = res->d; + } + + if (rsize >= msize) { + mpihelp_divrem(rp + msize, 0, rp, rsize, mp, msize); + rsize = msize; + } + + /* Remove any leading zero words from the result. */ + if (mod_shift_cnt) + mpihelp_rshift(rp, rp, rsize, mod_shift_cnt); + MPN_NORMALIZE(rp, rsize); + } + + if (negative_result && rsize) { + if (mod_shift_cnt) + mpihelp_rshift(mp, mp, msize, mod_shift_cnt); + mpihelp_sub(rp, mp, msize, rp, rsize); + rsize = msize; + rsign = msign; + MPN_NORMALIZE(rp, rsize); + } + res->nlimbs = rsize; + res->sign = rsign; + +leave: + rc = 0; +enomem: + mpihelp_release_karatsuba_ctx(&karactx); + if (assign_rp) + mpi_assign_limb_space(res, rp, size); + if (mp_marker) + mpi_free_limb_space(mp_marker); + if (bp_marker) + mpi_free_limb_space(bp_marker); + if (ep_marker) + mpi_free_limb_space(ep_marker); + if (xp_marker) + mpi_free_limb_space(xp_marker); + if (tspace) + mpi_free_limb_space(tspace); + return rc; +} +EXPORT_SYMBOL_GPL(mpi_powm); -- cgit v1.3.1