From d61ef7352b0026d9eeaf457dbfbb2e3fd8401e92 Mon Sep 17 00:00:00 2001 From: Carlos O'Donell Date: Thu, 29 Sep 2016 21:54:31 -0400 Subject: Bug 20292 - Simplify and test _dl_addr_inside_object The function _dl_addr_inside_object is simplified by removing the conditional 'reladdr - l->l_phdr[n].p_vaddr >= 0' which is always true. The function is refactored into it's own object file and a unit test added to verify the correct behaviour of the function. --- elf/dl-addr-obj.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 elf/dl-addr-obj.c (limited to 'elf/dl-addr-obj.c') diff --git a/elf/dl-addr-obj.c b/elf/dl-addr-obj.c new file mode 100644 index 0000000000..f6407610d1 --- /dev/null +++ b/elf/dl-addr-obj.c @@ -0,0 +1,75 @@ +/* Determine if address is inside object load segments. + Copyright (C) 1996-2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include + +/* Return non-zero if ADDR lies within one of L's loadable segments. + We have three cases we care about. + + Case 1: addr is above a segment. + +==================+<- l_map_end + | |<- addr + |------------------|<- l_addr + p_vaddr + p_memsz + | | + | | + |------------------|<- l_addr + p_vaddr + |------------------|<- l_addr + | | + +==================+<- l_map_start + + Case 2: addr is within a segments. + +==================+<- l_map_end + | | + |------------------|<- l_addr + p_vaddr + p_memsz + | |<- addr + | | + |------------------|<- l_addr + p_vaddr + |------------------|<- l_addr + | | + +==================+<- l_map_start + + Case 3: addr is below a segments. + +==================+<- l_map_end + | | + |------------------|<- l_addr + p_vaddr + p_memsz + | | + | | + |------------------|<- l_addr + p_vaddr + |------------------|<- l_addr + | |<- addr + +==================+<- l_map_start + + All the arithmetic is unsigned and we shift all the values down by + l_addr + p_vaddr and then compare the normalized addr to the range + of interest i.e. 0 <= addr < p_memsz. + +*/ +int +internal_function +_dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr) +{ + int n = l->l_phnum; + const ElfW(Addr) reladdr = addr - l->l_addr; + + while (--n >= 0) + if (l->l_phdr[n].p_type == PT_LOAD + && reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz) + return 1; + return 0; +} -- cgit 1.4.1