Contents of /trunk/grub/patches/grub-2.02-binutils-2.27-support-modules-without-symbol-table.patch
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Tue Apr 4 09:31:09 2017 UTC (7 years, 5 months ago) by niro
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Tue Apr 4 09:31:09 2017 UTC (7 years, 5 months ago) by niro
File size: 4440 byte(s)
-renamed
1 | [PATCH v2] support modules without symbol table |
2 | |
3 | From: Andrei Borzenkov |
4 | Subject: [PATCH v2] support modules without symbol table |
5 | Date: Wed, 3 Feb 2016 20:01:24 +0300 |
6 | all_video module does not have any code or data and exists solely for |
7 | .moddeps section to pull in dependencies. This makes all symbols unneeded. |
8 | |
9 | While in current binutils (last released version as of this commit is 2.26) |
10 | ``strip --strip-unneeded'' unintentionally adds section symbols for each |
11 | existing section, this behavior was considered a bug and changed in commit |
12 | 14f2c699ddca1e2f706342dffc59a6c7e23e844c to completely strip symbol table |
13 | in this case. |
14 | |
15 | Older binutils (verified with 2.17) and some other toolchains (at least |
16 | elftoolchain r3223M), both used in FreeBSD, remove symbol table in all_video |
17 | as well. |
18 | |
19 | Relax run-time check and do not return error for modules without symbol table. |
20 | Add additional checks to module verifier to make sure such modules |
21 | |
22 | a) have non-empty .moddeps section. Without either externally visible symbols |
23 | or .moddeps modules are completely useless and should not be built. |
24 | |
25 | b) do not have any relocations. |
26 | |
27 | Closes: 46986 |
28 | |
29 | v2: add run-time check for empty symbol table if relocations are present as |
30 | suggested by Vladimir. |
31 | |
32 | --- |
33 | grub-core/kern/dl.c | 8 +++++++- |
34 | util/grub-module-verifierXX.c | 19 ++++++++++++++++++- |
35 | 2 files changed, 25 insertions(+), 2 deletions(-) |
36 | |
37 | diff --git a/grub-core/kern/dl.c b/grub-core/kern/dl.c |
38 | index 59a6ef4..e394cd9 100644 |
39 | --- a/grub-core/kern/dl.c |
40 | +++ b/grub-core/kern/dl.c |
41 | @@ -333,8 +333,11 @@ grub_dl_resolve_symbols (grub_dl_t mod, Elf_Ehdr *e) |
42 | if (s->sh_type == SHT_SYMTAB) |
43 | break; |
44 | |
45 | + /* Module without symbol table may still be used to pull in dependencies. |
46 | + We verify at build time that such modules do not contain any relocations |
47 | + that may reference symbol table. */ |
48 | if (i == e->e_shnum) |
49 | - return grub_error (GRUB_ERR_BAD_MODULE, N_("no symbol table")); |
50 | + return GRUB_ERR_NONE; |
51 | |
52 | #ifdef GRUB_MODULES_MACHINE_READONLY |
53 | mod->symtab = grub_malloc (s->sh_size); |
54 | @@ -576,6 +579,9 @@ grub_dl_relocate_symbols (grub_dl_t mod, void *ehdr) |
55 | |
56 | if (seg) |
57 | { |
58 | + if (!mod->symtab) |
59 | + return grub_error (GRUB_ERR_BAD_MODULE, "relocation without |
60 | symbol table"); |
61 | + |
62 | err = grub_arch_dl_relocate_symbols (mod, ehdr, s, seg); |
63 | if (err) |
64 | return err; |
65 | diff --git a/util/grub-module-verifierXX.c b/util/grub-module-verifierXX.c |
66 | index f612d51..f8c15b0 100644 |
67 | --- a/util/grub-module-verifierXX.c |
68 | +++ b/util/grub-module-verifierXX.c |
69 | @@ -176,7 +176,7 @@ get_symtab (const struct grub_module_verifier_arch *arch, |
70 | Elf_Ehdr *e, Elf_Word |
71 | break; |
72 | |
73 | if (i == grub_target_to_host16 (e->e_shnum)) |
74 | - grub_util_error ("no symbol table"); |
75 | + return NULL; |
76 | |
77 | sym = (Elf_Sym *) ((char *) e + grub_target_to_host (s->sh_offset)); |
78 | *size = grub_target_to_host (s->sh_size); |
79 | @@ -191,7 +191,21 @@ check_symbols (const struct grub_module_verifier_arch |
80 | *arch, Elf_Ehdr *e) |
81 | Elf_Word size, entsize; |
82 | unsigned i; |
83 | |
84 | + /* Module without symbol table and without .moddeps section is useless |
85 | + at boot time, so catch it early to prevent build errors */ |
86 | sym = get_symtab (arch, e, &size, &entsize); |
87 | + if (!sym) |
88 | + { |
89 | + Elf_Shdr *s = find_section (arch, e, ".moddeps"); |
90 | + |
91 | + if (!s) |
92 | + grub_util_error ("no symbol table and no .moddeps section"); |
93 | + |
94 | + if (!s->sh_size) |
95 | + grub_util_error ("no symbol table and empty .moddeps section"); |
96 | + |
97 | + return; |
98 | + } |
99 | |
100 | for (i = 0; |
101 | i < size / entsize; |
102 | @@ -243,6 +257,8 @@ section_check_relocations (const struct |
103 | grub_module_verifier_arch *arch, void *e |
104 | Elf_Word symtabsize, symtabentsize; |
105 | |
106 | symtab = get_symtab (arch, ehdr, &symtabsize, &symtabentsize); |
107 | + if (!symtab) |
108 | + grub_util_error ("relocation without symbol table"); |
109 | |
110 | for (rel = (Elf_Rel *) ((char *) ehdr + grub_target_to_host (s->sh_offset)), |
111 | max = (Elf_Rel *) ((char *) rel + grub_target_to_host (s->sh_size)); |
112 | @@ -272,6 +288,7 @@ section_check_relocations (const struct |
113 | grub_module_verifier_arch *arch, void *e |
114 | break; |
115 | if (arch->short_relocations[i] == -1) |
116 | grub_util_error ("unsupported relocation 0x%x", type); |
117 | + |
118 | sym = (Elf_Sym *) ((char *) symtab + symtabentsize * ELF_R_SYM |
119 | (grub_target_to_host (rel->r_info))); |
120 | |
121 | if (is_symbol_local (sym)) |
122 | -- |
123 | tg: (7290bb5..) bug/46986 (depends on: master) |
124 |