1/* Determine if address is inside object load segments.
2 Copyright (C) 1996-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <link.h>
20#include <elf.h>
21
22/* Return non-zero if ADDR lies within one of L's loadable segments.
23 We have three cases we care about.
24
25 Case 1: addr is above a segment.
26 +==================+<- l_map_end
27 | |<- addr
28 |------------------|<- l_addr + p_vaddr + p_memsz
29 | |
30 | |
31 |------------------|<- l_addr + p_vaddr
32 |------------------|<- l_addr
33 | |
34 +==================+<- l_map_start
35
36 Case 2: addr is within a segments.
37 +==================+<- l_map_end
38 | |
39 |------------------|<- l_addr + p_vaddr + p_memsz
40 | |<- addr
41 | |
42 |------------------|<- l_addr + p_vaddr
43 |------------------|<- l_addr
44 | |
45 +==================+<- l_map_start
46
47 Case 3: addr is below a segments.
48 +==================+<- l_map_end
49 | |
50 |------------------|<- l_addr + p_vaddr + p_memsz
51 | |
52 | |
53 |------------------|<- l_addr + p_vaddr
54 |------------------|<- l_addr
55 | |<- addr
56 +==================+<- l_map_start
57
58 All the arithmetic is unsigned and we shift all the values down by
59 l_addr + p_vaddr and then compare the normalized addr to the range
60 of interest i.e. 0 <= addr < p_memsz.
61
62*/
63int
64_dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr)
65{
66 int n = l->l_phnum;
67 const ElfW(Addr) reladdr = addr - l->l_addr;
68
69 while (--n >= 0)
70 if (l->l_phdr[n].p_type == PT_LOAD
71 && reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz)
72 return 1;
73 return 0;
74}
75